CWE-178
AllowedImproper Handling of Case Sensitivity
Abstraction: Base · Status: Incomplete
The product does not properly account for differences in case sensitivity when accessing or determining the properties of a resource, leading to inconsistent results.
177 vulnerabilities reference this CWE, most recent first.
GHSA-52QV-5PM8-P78H
Vulnerability from github – Published: 2021-12-16 00:01 – Updated: 2021-12-18 00:01In isFileUri of UriUtil.java, there is a possible way to bypass ignoring file://URI attachment due to improper handling of case sensitivity. This could lead to local information disclosure with no additional execution privileges needed. User interaction is needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-197328178
{
"affected": [],
"aliases": [
"CVE-2021-0973"
],
"database_specific": {
"cwe_ids": [
"CWE-178"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-12-15T19:15:00Z",
"severity": "MODERATE"
},
"details": "In isFileUri of UriUtil.java, there is a possible way to bypass ignoring file://URI attachment due to improper handling of case sensitivity. This could lead to local information disclosure with no additional execution privileges needed. User interaction is needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-197328178",
"id": "GHSA-52qv-5pm8-p78h",
"modified": "2021-12-18T00:01:29Z",
"published": "2021-12-16T00:01:16Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-0973"
},
{
"type": "WEB",
"url": "https://source.android.com/security/bulletin/pixel/2021-12-01"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-59MM-6RR4-J9P2
Vulnerability from github – Published: 2023-12-07 03:30 – Updated: 2026-05-12 12:31This flaw allows a malicious HTTP server to set "super cookies" in curl that are then passed back to more origins than what is otherwise allowed or possible. This allows a site to set cookies that then would get sent to different and unrelated sites and domains.
It could do this by exploiting a mixed case flaw in curl's function that
verifies a given cookie domain against the Public Suffix List (PSL). For
example a cookie could be set with domain=co.UK when the URL used a lower
case hostname curl.co.uk, even though co.uk is listed as a PSL domain.
{
"affected": [],
"aliases": [
"CVE-2023-46218"
],
"database_specific": {
"cwe_ids": [
"CWE-178"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-12-07T01:15:07Z",
"severity": "MODERATE"
},
"details": "This flaw allows a malicious HTTP server to set \"super cookies\" in curl that\nare then passed back to more origins than what is otherwise allowed or\npossible. This allows a site to set cookies that then would get sent to\ndifferent and unrelated sites and domains.\n\nIt could do this by exploiting a mixed case flaw in curl\u0027s function that\nverifies a given cookie domain against the Public Suffix List (PSL). For\nexample a cookie could be set with `domain=co.UK` when the URL used a lower\ncase hostname `curl.co.uk`, even though `co.uk` is listed as a PSL domain.",
"id": "GHSA-59mm-6rr4-j9p2",
"modified": "2026-05-12T12:31:33Z",
"published": "2023-12-07T03:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-46218"
},
{
"type": "WEB",
"url": "https://hackerone.com/reports/2212193"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-093430.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-202008.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-331112.html"
},
{
"type": "WEB",
"url": "https://curl.se/docs/CVE-2023-46218.html"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2023/12/msg00015.html"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3ZX3VW67N4ACRAPMV2QS2LVYGD7H2MVE"
},
{
"type": "WEB",
"url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UOGXU25FMMT2X6UUITQ7EZZYMJ42YWWD"
},
{
"type": "WEB",
"url": "https://security.netapp.com/advisory/ntap-20240125-0007"
},
{
"type": "WEB",
"url": "https://www.debian.org/security/2023/dsa-5587"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-5MP6-JRQ3-R938
Vulnerability from github – Published: 2026-05-12 18:30 – Updated: 2026-05-18 20:31Improper Handling of Case Sensitivity vulnerability in LockOutRealm in Apache Tomcat.
This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.21, from 10.1.0-M1 through 10.1.54, from 9.0.0.M1 through 9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. Older unsupported versions may also be affected.
Users are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.tomcat.embed:tomcat-embed-core"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "9.0.118"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.tomcat.embed:tomcat-embed-core"
},
"ranges": [
{
"events": [
{
"introduced": "10.1.0-M1"
},
{
"fixed": "10.1.55"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.tomcat.embed:tomcat-embed-core"
},
"ranges": [
{
"events": [
{
"introduced": "11.0.0-M1"
},
{
"fixed": "11.0.22"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.tomcat:tomcat"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "9.0.118"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.tomcat:tomcat"
},
"ranges": [
{
"events": [
{
"introduced": "10.1.0-M1"
},
{
"fixed": "10.1.55"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.tomcat:tomcat"
},
"ranges": [
{
"events": [
{
"introduced": "11.0.0-M1"
},
{
"fixed": "11.0.22"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.tomcat:tomcat-catalina"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "9.0.118"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.tomcat:tomcat-catalina"
},
"ranges": [
{
"events": [
{
"introduced": "10.1.0-M1"
},
{
"fixed": "10.1.55"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.tomcat:tomcat-catalina"
},
"ranges": [
{
"events": [
{
"introduced": "11.0.0-M1"
},
{
"fixed": "11.0.22"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-43513"
],
"database_specific": {
"cwe_ids": [
"CWE-178"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-18T20:31:54Z",
"nvd_published_at": "2026-05-12T16:16:18Z",
"severity": "HIGH"
},
"details": "Improper Handling of Case Sensitivity vulnerability in LockOutRealm in Apache Tomcat.\n\nThis issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.21, from 10.1.0-M1 through 10.1.54, from 9.0.0.M1 through 9.0.117, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109.\nOlder unsupported versions may also be affected.\n\nUsers are recommended to upgrade to version 11.0.22, 10.1.55 or 9.0.118 which fix the issue.",
"id": "GHSA-5mp6-jrq3-r938",
"modified": "2026-05-18T20:31:54Z",
"published": "2026-05-12T18:30:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43513"
},
{
"type": "WEB",
"url": "https://github.com/apache/tomcat/commit/4a90d3fa93988c447cd5bb7482f76ff70d7f15c2"
},
{
"type": "WEB",
"url": "https://github.com/apache/tomcat/commit/6dd75beb55bd42fc5f78e929596b25018cd17717"
},
{
"type": "WEB",
"url": "https://github.com/apache/tomcat/commit/83f3e51df7b87f5f6e626951c575ded1a512e8ef"
},
{
"type": "PACKAGE",
"url": "https://github.com/apache/tomcat"
},
{
"type": "WEB",
"url": "https://lists.apache.org/thread/ytjcgldshj73lcnd1sh95od5hrghwogp"
},
{
"type": "WEB",
"url": "https://tomcat.apache.org/security-10.html"
},
{
"type": "WEB",
"url": "https://tomcat.apache.org/security-11.html"
},
{
"type": "WEB",
"url": "https://tomcat.apache.org/security-9.html"
},
{
"type": "WEB",
"url": "http://www.openwall.com/lists/oss-security/2026/05/12/9"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Apache Tomcat: LockOutRealm treats user names as case-sensitive"
}
GHSA-5MRR-24GH-4JWH
Vulnerability from github – Published: 2026-09-06 12:30 – Updated: 2026-09-06 12:30PocketMine-MP before 4.0.3 does not perform case-insensitive matching when removing operator entries from ops.txt. The removeOp function lowercases the supplied name but only removes an exactly matching entry, so an operator name stored with non-lowercase letters cannot be revoked using the deop command, leaving the player as an operator until the entry is removed from ops.txt manually.
{
"affected": [],
"aliases": [
"CVE-2021-48006"
],
"database_specific": {
"cwe_ids": [
"CWE-178"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-06T12:17:14Z",
"severity": "MODERATE"
},
"details": "PocketMine-MP before 4.0.3 does not perform case-insensitive matching when removing operator entries from ops.txt. The removeOp function lowercases the supplied name but only removes an exactly matching entry, so an operator name stored with non-lowercase letters cannot be revoked using the deop command, leaving the player as an operator until the entry is removed from ops.txt manually.",
"id": "GHSA-5mrr-24gh-4jwh",
"modified": "2026-09-06T12:30:23Z",
"published": "2026-09-06T12:30:23Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pmmp/PocketMine-MP/security/advisories/GHSA-j5qg-w9jg-3wg3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-48006"
},
{
"type": "WEB",
"url": "https://github.com/pmmp/PocketMine-MP/commit/4d37b79ff7f9d9452e988387f97919a9a1c4954e"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/pocketmine-mp-before-4.0.3-operator-privilege-escalation-via-case-sensitivity"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-5MV9-76R9-RPRQ
Vulnerability from github – Published: 2026-07-17 03:31 – Updated: 2026-07-17 03:31Grav before 2.0.4 ships a default .htaccess (and reference webserver-configs/htaccess.txt) whose rules blocking access to sensitive file types (.yaml, .php, .json, etc.) lack the [NC] flag, making extension matching case-sensitive. On case-insensitive filesystems (Windows/NTFS, macOS/HFS+, or Docker volume mounts), an unauthenticated attacker can request these files with uppercase or mixed-case extensions (e.g., .YAML, .PHP) to bypass the restrictions and read sensitive configuration files that may contain API keys and credentials.
{
"affected": [],
"aliases": [
"CVE-2026-62230"
],
"database_specific": {
"cwe_ids": [
"CWE-178"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-17T02:18:10Z",
"severity": "HIGH"
},
"details": "Grav before 2.0.4 ships a default .htaccess (and reference webserver-configs/htaccess.txt) whose rules blocking access to sensitive file types (.yaml, .php, .json, etc.) lack the [NC] flag, making extension matching case-sensitive. On case-insensitive filesystems (Windows/NTFS, macOS/HFS+, or Docker volume mounts), an unauthenticated attacker can request these files with uppercase or mixed-case extensions (e.g., .YAML, .PHP) to bypass the restrictions and read sensitive configuration files that may contain API keys and credentials.",
"id": "GHSA-5mv9-76r9-rprq",
"modified": "2026-07-17T03:31:23Z",
"published": "2026-07-17T03:31:23Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/getgrav/grav/security/advisories/GHSA-vwg3-w8w3-pc79"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-62230"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/grav-file-access-bypass-via-case-variation"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-5VX9-J5CW-47VQ
Vulnerability from github – Published: 2023-02-17 18:30 – Updated: 2023-03-01 01:35Authentication vulnerability in MOSN before v.0.23.0 allows attacker to escalate privileges via case-sensitive JWT authorization.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "mosn.io/mosn"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.23.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-32163"
],
"database_specific": {
"cwe_ids": [
"CWE-178",
"CWE-863"
],
"github_reviewed": true,
"github_reviewed_at": "2023-02-17T20:47:37Z",
"nvd_published_at": "2023-02-17T18:15:00Z",
"severity": "CRITICAL"
},
"details": "Authentication vulnerability in MOSN before v.0.23.0 allows attacker to escalate privileges via case-sensitive JWT authorization.",
"id": "GHSA-5vx9-j5cw-47vq",
"modified": "2023-03-01T01:35:47Z",
"published": "2023-02-17T18:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-32163"
},
{
"type": "WEB",
"url": "https://github.com/mosn/mosn/issues/1633"
},
{
"type": "WEB",
"url": "https://github.com/mosn/mosn/pull/1637"
},
{
"type": "PACKAGE",
"url": "https://github.com/mosn/mosn"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "Privilege escalation in MOSN"
}
GHSA-6C7R-27GF-58JJ
Vulnerability from github – Published: 2022-04-30 18:21 – Updated: 2024-02-15 21:31register.php in Ultimate PHP Board (UPB) 1.0 and 1.0b uses an administrative account Admin with a capital "A," but allows a remote attacker to impersonate the administrator by registering an account name of admin with a lower case "a."
{
"affected": [],
"aliases": [
"CVE-2002-1820"
],
"database_specific": {
"cwe_ids": [
"CWE-178"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2002-12-31T05:00:00Z",
"severity": "HIGH"
},
"details": "register.php in Ultimate PHP Board (UPB) 1.0 and 1.0b uses an administrative account Admin with a capital \"A,\" but allows a remote attacker to impersonate the administrator by registering an account name of admin with a lower case \"a.\"",
"id": "GHSA-6c7r-27gf-58jj",
"modified": "2024-02-15T21:31:22Z",
"published": "2022-04-30T18:21:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2002-1820"
},
{
"type": "WEB",
"url": "http://www.iss.net/security_center/static/9972.php"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/archive/1/289417"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/5580"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-6J7G-HR6V-3HXC
Vulnerability from github – Published: 2026-08-05 15:32 – Updated: 2026-08-05 18:31A flaw was found in Keycloak's Authorization Services. The component responsible for matching request paths to security policies (PathMatcher) does not properly normalize URIs before comparison. By adding extra characters like a trailing slash or matrix parameters to a URL, an attacker can trick the system into applying a less restrictive security policy than intended. This allows an authenticated user to access administrative or restricted areas they should not have permission to see.
{
"affected": [],
"aliases": [
"CVE-2026-15573"
],
"database_specific": {
"cwe_ids": [
"CWE-178",
"CWE-551"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-05T15:16:36Z",
"severity": "HIGH"
},
"details": "A flaw was found in Keycloak\u0027s Authorization Services. The component responsible for matching request paths to security policies (PathMatcher) does not properly normalize URIs before comparison. By adding extra characters like a trailing slash or matrix parameters to a URL, an attacker can trick the system into applying a less restrictive security policy than intended. This allows an authenticated user to access administrative or restricted areas they should not have permission to see.",
"id": "GHSA-6j7g-hr6v-3hxc",
"modified": "2026-08-05T18:31:34Z",
"published": "2026-08-05T15:32:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-15573"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:50846"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:50847"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:50848"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:50849"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-15573"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2499593"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-6MJ3-QW4J-HGRW
Vulnerability from github – Published: 2026-09-08 20:59 – Updated: 2026-09-08 20:59Summary
In HTML mode (text/html), a raw-text element (script, style, textarea, title) whose closing
tag differs in case from its opening tag (e.g. </ScRiPt> for <script>) is mishandled by the
parser, producing quadratic (O(n²)) output growth — a small crafted document parses and serializes
into output orders of magnitude larger, exhausting CPU and memory. A modest input of tens of KB can
therefore cause a denial of service in any service that parses untrusted HTML with xmldom. Only HTML
mode is affected.
Details
The parser calls parseHtmlSpecialContent for each raw-text element in HTML mode, matched via
isHTMLRawTextElement / isHTMLEscapableRawTextElement (so all four types — script, style,
textarea, title — are in scope). It searches for the element's closing tag with
source.indexOf('</' + tagName + '>', elStartEnd), a byte-for-byte case-sensitive match. A
mixed-case closing tag never matches, so the search returns -1, and the following
source.substring(elStartEnd + 1, -1) extracts text backwards from the start of the document
instead of the element's content. The function then returns -1 to the parse loop, which cannot
advance normally and falls back to character-by-character reprocessing. Every raw-text element
re-captures all source text preceding it, so output grows as O(n²) in the number of such elements.
Root Cause
- Case-sensitive close-tag search (
lib/sax.js:549):source.indexOf('</' + tagName + '>', elStartEnd)does not fold case, contrary to the WHATWG HTML RAWTEXT end-tag-name rule. - Unguarded
-1(lib/sax.js:550):source.substring(elStartEnd + 1, elEndStart)runs even whenelEndStart === -1, extracting text backwards from position 0. - Unstable progression (
lib/sax.js:556): the function returnselEndStart(-1), driving repeated character-by-character fallback in the parse loop.
Affected Versions
Only the 0.9.x line is affected — the amplification was introduced in 0.9.0-beta.1 when
parseHtmlSpecialContent was refactored, and remains through 0.9.11. The 0.8.x line is not
affected: its older parseHtmlSpecialContent does not amplify, despite sharing the same
case-sensitive indexOf.
Proof of Concept
const { DOMParser, XMLSerializer } = require('@xmldom/xmldom');
const n = 1000;
const payload = '<html><body>' + '<script>x</ScRiPt>'.repeat(n) + '</body></html>';
const doc = new DOMParser().parseFromString(payload, 'text/html');
const out = new XMLSerializer().serializeToString(doc);
console.log(payload.length, out.length, (out.length / payload.length).toFixed(1) + 'x');
// 18026 9037063 501.3x — an 18 KB input yields ~9 MB of output
Output size grows quadratically with the number of case-mismatched raw-text elements:
Repeats | Input len | Output len | Ratio
1 | 44 | 109 | 2.5x
100 | 1826 | 93763 | 51.3x
500 | 9026 | 2268563 | 251.3x
1000 | 18026 | 9037063 | 501.3x
2000 | 36026 | 36074063 | 1001.3x
Proof of Concept from @KarimTantawey (tested with script); the same amplification occurs for style,
textarea, and title.
Impact
Small attacker payloads can force disproportionate CPU and memory usage in services that parse and serialize untrusted HTML via xmldom. The quadratic growth means a modest-sized input (tens of kilobytes) can produce output in the tens or hundreds of megabytes, potentially exhausting memory or causing timeouts.
The attack only requires HTML mode (text/html MIME type) and mixed-case closing tags for
any of the four raw-text element types. No special configuration or error handler setup is needed.
Severity note
The CVSS 4.0 vector scores availability only (VA:H, with VC:N/VI:N): the flaw neither discloses
nor corrupts data, but a small untrusted HTML input (tens of KB) can force output and memory in the
tens to hundreds of MB, enough to exhaust a service's heap or stall its event loop. It is reachable
with no authentication, configuration, or error-handler setup — only that the application parses
untrusted text/html and serializes the result.
Fix Applied
The raw-text closing tag is now matched case-insensitively in HTML raw-text mode (per the WHATWG HTML RAWTEXT end-tag rule), and a missing closing tag is handled explicitly, removing the quadratic output amplification. Output for well-formed input is unchanged. Non-breaking; 0.9.x-only.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.9.11"
},
"package": {
"ecosystem": "npm",
"name": "@xmldom/xmldom"
},
"ranges": [
{
"events": [
{
"introduced": "0.9.0-beta.1"
},
{
"fixed": "0.9.12"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-83612"
],
"database_specific": {
"cwe_ids": [
"CWE-178",
"CWE-400"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-08T20:59:54Z",
"nvd_published_at": "2026-09-01T15:17:39Z",
"severity": "HIGH"
},
"details": "## Summary\n\nIn HTML mode (`text/html`), a raw-text element (`script`, `style`, `textarea`, `title`) whose closing\ntag differs in case from its opening tag (e.g. `\u003c/ScRiPt\u003e` for `\u003cscript\u003e`) is mishandled by the\nparser, producing quadratic (O(n\u00b2)) output growth \u2014 a small crafted document parses and serializes\ninto output orders of magnitude larger, exhausting CPU and memory. A modest input of tens of KB can\ntherefore cause a denial of service in any service that parses untrusted HTML with xmldom. Only HTML\nmode is affected.\n\n## Details\n\nThe parser calls `parseHtmlSpecialContent` for each raw-text element in HTML mode, matched via\n`isHTMLRawTextElement` / `isHTMLEscapableRawTextElement` (so all four types \u2014 `script`, `style`,\n`textarea`, `title` \u2014 are in scope). It searches for the element\u0027s closing tag with\n`source.indexOf(\u0027\u003c/\u0027 + tagName + \u0027\u003e\u0027, elStartEnd)`, a byte-for-byte case-sensitive match. A\nmixed-case closing tag never matches, so the search returns `-1`, and the following\n`source.substring(elStartEnd + 1, -1)` extracts text backwards from the start of the document\ninstead of the element\u0027s content. The function then returns `-1` to the parse loop, which cannot\nadvance normally and falls back to character-by-character reprocessing. Every raw-text element\nre-captures all source text preceding it, so output grows as O(n\u00b2) in the number of such elements.\n\n### Root Cause\n\n1. **Case-sensitive close-tag search** (`lib/sax.js:549`): `source.indexOf(\u0027\u003c/\u0027 + tagName + \u0027\u003e\u0027,\n elStartEnd)` does not fold case, contrary to the WHATWG HTML RAWTEXT end-tag-name rule.\n2. **Unguarded `-1`** (`lib/sax.js:550`): `source.substring(elStartEnd + 1, elEndStart)` runs even\n when `elEndStart === -1`, extracting text backwards from position 0.\n3. **Unstable progression** (`lib/sax.js:556`): the function returns `elEndStart` (`-1`), driving\n repeated character-by-character fallback in the parse loop.\n\n## Affected Versions\n\nOnly the `0.9.x` line is affected \u2014 the amplification was introduced in `0.9.0-beta.1` when\n`parseHtmlSpecialContent` was refactored, and remains through `0.9.11`. The `0.8.x` line is **not**\naffected: its older `parseHtmlSpecialContent` does not amplify, despite sharing the same\ncase-sensitive `indexOf`.\n\n## Proof of Concept\n\n```js\nconst { DOMParser, XMLSerializer } = require(\u0027@xmldom/xmldom\u0027);\n\nconst n = 1000;\nconst payload = \u0027\u003chtml\u003e\u003cbody\u003e\u0027 + \u0027\u003cscript\u003ex\u003c/ScRiPt\u003e\u0027.repeat(n) + \u0027\u003c/body\u003e\u003c/html\u003e\u0027;\nconst doc = new DOMParser().parseFromString(payload, \u0027text/html\u0027);\nconst out = new XMLSerializer().serializeToString(doc);\nconsole.log(payload.length, out.length, (out.length / payload.length).toFixed(1) + \u0027x\u0027);\n// 18026 9037063 501.3x \u2014 an 18 KB input yields ~9 MB of output\n```\n\nOutput size grows quadratically with the number of case-mismatched raw-text elements:\n\n```\nRepeats | Input len | Output len | Ratio\n1 | 44 | 109 | 2.5x\n100 | 1826 | 93763 | 51.3x\n500 | 9026 | 2268563 | 251.3x\n1000 | 18026 | 9037063 | 501.3x\n2000 | 36026 | 36074063 | 1001.3x\n```\n\nProof of Concept from @KarimTantawey (tested with `script`); the same amplification occurs for `style`,\n`textarea`, and `title`.\n\n## Impact\n\nSmall attacker payloads can force disproportionate CPU and memory usage in services that\nparse and serialize untrusted HTML via xmldom. The quadratic growth means a modest-sized input\n(tens of kilobytes) can produce output in the tens or hundreds of megabytes, potentially\nexhausting memory or causing timeouts.\n\nThe attack only requires HTML mode (`text/html` MIME type) and mixed-case closing tags for\nany of the four raw-text element types. No special configuration or error handler setup is needed.\n\n## Severity note\n\nThe CVSS 4.0 vector scores availability only (`VA:H`, with `VC:N/VI:N`): the flaw neither discloses\nnor corrupts data, but a small untrusted HTML input (tens of KB) can force output and memory in the\ntens to hundreds of MB, enough to exhaust a service\u0027s heap or stall its event loop. It is reachable\nwith no authentication, configuration, or error-handler setup \u2014 only that the application parses\nuntrusted `text/html` and serializes the result.\n\n## Fix Applied\n\nThe raw-text closing tag is now matched case-insensitively in HTML raw-text mode (per the WHATWG HTML\n[RAWTEXT end-tag rule](https://html.spec.whatwg.org/multipage/parsing.html#rawtext-end-tag-name-state)),\nand a missing closing tag is handled explicitly, removing the quadratic output amplification. Output\nfor well-formed input is unchanged. Non-breaking; 0.9.x-only.",
"id": "GHSA-6mj3-qw4j-hgrw",
"modified": "2026-09-08T20:59:54Z",
"published": "2026-09-08T20:59:54Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/xmldom/xmldom/security/advisories/GHSA-6mj3-qw4j-hgrw"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-83612"
},
{
"type": "WEB",
"url": "https://github.com/xmldom/xmldom/pull/1071"
},
{
"type": "WEB",
"url": "https://github.com/xmldom/xmldom/commit/7ced40c06c28d151e996a97045018c3559ae4707"
},
{
"type": "PACKAGE",
"url": "https://github.com/xmldom/xmldom"
},
{
"type": "WEB",
"url": "https://github.com/xmldom/xmldom/releases/tag/0.9.12"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "xmldom: HTML raw-text closing-tag case mismatch causes output amplification"
}
GHSA-6RGH-57XM-37V8
Vulnerability from github – Published: 2026-04-30 18:30 – Updated: 2026-09-14 15:32A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of nameConstraints labels, specifically for dNSName (DNS) or rfc822Name (email) constraints within excludedSubtrees or permittedSubtrees. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.
{
"affected": [],
"aliases": [
"CVE-2026-3833"
],
"database_specific": {
"cwe_ids": [
"CWE-178"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-30T18:16:30Z",
"severity": "MODERATE"
},
"details": "A flaw was found in gnutls. This vulnerability occurs because gnutls performs case-sensitive comparisons of `nameConstraints` labels, specifically for `dNSName` (DNS) or `rfc822Name` (email) constraints within `excludedSubtrees` or `permittedSubtrees`. A remote attacker can exploit this by crafting a leaf certificate with casing differences in the Subject Alternative Name (SAN), leading to a policy bypass where a certificate that should be rejected is instead accepted. This could result in unauthorized access or information disclosure.",
"id": "GHSA-6rgh-57xm-37v8",
"modified": "2026-09-14T15:32:02Z",
"published": "2026-04-30T18:30:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-3833"
},
{
"type": "WEB",
"url": "https://gitlab.com/gnutls/gnutls/-/issues/1803"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2445763"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-3833"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:62549"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:62409"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:60019"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:59831"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:58981"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:57402"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:43575"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:41921"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:33125"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:32962"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:30850"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:30849"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:30004"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:29197"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:26409"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:26319"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:20613"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:20612"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:20611"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:13274"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
Mitigation MIT-44
Strategy: Input Validation
Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
Mitigation MIT-5
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Mitigation MIT-20
Strategy: Input Validation
Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
No CAPEC attack patterns related to this CWE.