Vulnerability-Lookup

CVE-2026-45309 (GCVE-0-2026-45309)

Vulnerability from cvelistv5 – Published: 2026-07-17 18:40 – Updated: 2026-07-17 18:40

Title

AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username

Summary

AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Prior to 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.

Severity

8.2 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Assigner

GitHub_M

References

3 references

URL	Tags
https://github.com/ronf/asyncssh/security/advisor…	x_refsource_CONFIRM
https://github.com/ronf/asyncssh/commit/2af2382cc…	x_refsource_MISC
https://github.com/ronf/asyncssh/commit/3d515ba9b…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
ronf	asyncssh	Affected: < 2.23.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "asyncssh",
          "vendor": "ronf",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.23.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Prior to 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \\, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-17T18:40:02.428Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/ronf/asyncssh/security/advisories/GHSA-g794-3fmp-753h",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/ronf/asyncssh/security/advisories/GHSA-g794-3fmp-753h"
        },
        {
          "name": "https://github.com/ronf/asyncssh/commit/2af2382cce946c959a378a62f257af253dc4ab51",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/ronf/asyncssh/commit/2af2382cce946c959a378a62f257af253dc4ab51"
        },
        {
          "name": "https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88"
        }
      ],
      "source": {
        "advisory": "GHSA-g794-3fmp-753h",
        "discovery": "UNKNOWN"
      },
      "title": "AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-45309",
    "datePublished": "2026-07-17T18:40:02.428Z",
    "dateReserved": "2026-05-11T20:14:43.203Z",
    "dateUpdated": "2026-07-17T18:40:02.428Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-45309",
      "date": "2026-07-19",
      "epss": "0.00453",
      "percentile": "0.36573"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-45309\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-07-17T19:17:14.333\",\"lastModified\":\"2026-07-17T19:17:14.333\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"AsyncSSH is a Python package which provides an asynchronous client and server implementation of the SSHv2 protocol on top of the Python asyncio framework. Prior to 2.23.0, AsyncSSH expands the OpenSSH-compatible AuthorizedKeysFile %u token in asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, and asyncssh/misc.py with the raw SSH username during pre-authentication server config reload, allowing a server configured with AuthorizedKeysFile authorized_keys/%u to read an authorized-keys file outside the intended directory when the SSH username contains /, \\\\, or .. path traversal segments and authenticate with an attacker-selected key file. This issue is fixed in version 2.23.0.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"ronf\",\"product\":\"asyncssh\",\"versions\":[{\"version\":\"\u003c 2.23.0\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/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\",\"baseScore\":8.2,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"HIGH\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-22\"}]}],\"references\":[{\"url\":\"https://github.com/ronf/asyncssh/commit/2af2382cce946c959a378a62f257af253dc4ab51\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/ronf/asyncssh/commit/3d515ba9ba0cd9990d248bdf62bcf05d51261a88\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/ronf/asyncssh/security/advisories/GHSA-g794-3fmp-753h\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}

GHSA-G794-3FMP-753H

Vulnerability from github – Published: 2026-05-27 21:35 – Updated: 2026-05-27 21:35

Summary

AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username

Details

Summary

AsyncSSH 2.22.0 expands the OpenSSH-compatible AuthorizedKeysFile %u token with the raw SSH username during pre-authentication server config reload. A server configured with a documented per-user key pattern such as AuthorizedKeysFile authorized_keys/%u can be made to read an authorized-keys file outside the intended directory when the SSH username contains path traversal segments. If the attacker can place or reference a readable authorized-keys-format file containing their public key, the attacker can authenticate over SSH as the traversal username.

Affected Product

Package: asyncssh
Ecosystem: pip
Affected versions: confirmed on 2.22.0; exact lower bound not finalized
Tested version: 2.22.0
Audit commit/tag: tag v2.22.0, commit af5a81e669633d83d535163f93b6bf3f957c9238
PyPI sdist SHA256: c3ce72b01be4f97b40e62844dd384227e5ff5a401a3793007c42f86a5c8eb537

Vulnerability Details

CWE: CWE-22: Improper Limitation of a Pathname to a Restricted Directory
Component: AsyncSSH server config reload and public-key authentication (asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, asyncssh/misc.py)
Root cause: %u in AuthorizedKeysFile is expanded from the remote username without rejecting path separators or .. segments, and the resulting path is opened without constraining it to the intended authorized-keys directory.
Security boundary violated: the configured authorized-keys directory and public-key authentication trust boundary.
Direct impact: public-key authentication succeeds using an attacker-selected authorized-keys file outside the intended directory.
Chain impact, if any: none claimed; direct authentication impact is primary.

Attack Preconditions

The AsyncSSH server uses a config or equivalent pattern where AuthorizedKeysFile contains %u, for example AuthorizedKeysFile authorized_keys/%u.
Public-key authentication is enabled.
The attacker can place or reference a readable authorized-keys-format file outside the intended directory, such as a file in a world-writable or application-writable location.
The application does not separately reject usernames containing /, \, or .. before AsyncSSH uses the username for key-file selection.

Reproduction

The run-scoped evidence contains a safe localhost proof:

Start the proof harness saved at harness_app.py
Run exploit_proof.py through run_proof.sh
The harness creates sshd_config with AuthorizedKeysFile authorized_keys/%u, writes the attacker's public key to a file outside authorized_keys/, starts a real AsyncSSH server, and attempts two SSH logins.
Expected result: the normal username victim fails, while the traversal username authenticates with the same attacker key.

Observed proof output:

[CONTROL] username=victim success=False
[ATTACK] username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub success=True
[ATTACK] output=AUTH_BYPASS_SUCCESS username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub
PASS: traversal username authenticated with attacker-controlled authorized_keys file

Severity

6.9 (Medium)


                  
                    CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "asyncssh"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.22.0"
            },
            {
              "fixed": "2.23.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.22.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45309"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-27T21:35:06Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\nAsyncSSH 2.22.0 expands the OpenSSH-compatible `AuthorizedKeysFile` `%u` token with the raw SSH username during pre-authentication server config reload. A server configured with a documented per-user key pattern such as `AuthorizedKeysFile authorized_keys/%u` can be made to read an authorized-keys file outside the intended directory when the SSH username contains path traversal segments. If the attacker can place or reference a readable authorized-keys-format file containing their public key, the attacker can authenticate over SSH as the traversal username.\n\n## Affected Product\n- Package: asyncssh\n- Ecosystem: pip\n- Affected versions: confirmed on 2.22.0; exact lower bound not finalized\n- Tested version: 2.22.0\n- Audit commit/tag: tag `v2.22.0`, commit `af5a81e669633d83d535163f93b6bf3f957c9238`\n- PyPI sdist SHA256: `c3ce72b01be4f97b40e62844dd384227e5ff5a401a3793007c42f86a5c8eb537`\n\n## Vulnerability Details\n- CWE: CWE-22: Improper Limitation of a Pathname to a Restricted Directory\n- Component: AsyncSSH server config reload and public-key authentication (`asyncssh/config.py`, `asyncssh/connection.py`, `asyncssh/auth_keys.py`, `asyncssh/misc.py`)\n- Root cause: `%u` in `AuthorizedKeysFile` is expanded from the remote username without rejecting path separators or `..` segments, and the resulting path is opened without constraining it to the intended authorized-keys directory.\n- Security boundary violated: the configured authorized-keys directory and public-key authentication trust boundary.\n- Direct impact: public-key authentication succeeds using an attacker-selected authorized-keys file outside the intended directory.\n- Chain impact, if any: none claimed; direct authentication impact is primary.\n\n## Attack Preconditions\n- The AsyncSSH server uses a config or equivalent pattern where `AuthorizedKeysFile` contains `%u`, for example `AuthorizedKeysFile authorized_keys/%u`.\n- Public-key authentication is enabled.\n- The attacker can place or reference a readable authorized-keys-format file outside the intended directory, such as a file in a world-writable or application-writable location.\n- The application does not separately reject usernames containing `/`, `\\`, or `..` before AsyncSSH uses the username for key-file selection.\n\n## Reproduction\nThe run-scoped evidence contains a safe localhost proof:\n\n1. Start the proof harness saved at \n[harness_app.py](https://github.com/user-attachments/files/27232526/harness_app.py)\n\n2. Run \n[exploit_proof.py](https://github.com/user-attachments/files/27232538/exploit_proof.py)\nthrough \n[run_proof.sh](https://github.com/user-attachments/files/27232545/run_proof.sh)\n\n3. The harness creates `sshd_config` with `AuthorizedKeysFile authorized_keys/%u`, writes the attacker\u0027s public key to a file outside `authorized_keys/`, starts a real AsyncSSH server, and attempts two SSH logins.\n4. Expected result: the normal username `victim` fails, while the traversal username authenticates with the same attacker key.\n\nObserved proof output:\n\n```text\n[CONTROL] username=victim success=False\n[ATTACK] username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub success=True\n[ATTACK] output=AUTH_BYPASS_SUCCESS username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub\nPASS: traversal username authenticated with attacker-controlled authorized_keys file\n```",
  "id": "GHSA-g794-3fmp-753h",
  "modified": "2026-05-27T21:35:06Z",
  "published": "2026-05-27T21:35:06Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ronf/asyncssh/security/advisories/GHSA-g794-3fmp-753h"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ronf/asyncssh"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username"
}

PYSEC-2026-2384

Vulnerability from pysec - Published: 2026-07-13 15:19 - Updated: 2026-07-13 15:19

Details

Summary

Affected Product

Package: asyncssh
Ecosystem: pip
Affected versions: confirmed on 2.22.0; exact lower bound not finalized
Tested version: 2.22.0
Audit commit/tag: tag v2.22.0, commit af5a81e669633d83d535163f93b6bf3f957c9238
PyPI sdist SHA256: c3ce72b01be4f97b40e62844dd384227e5ff5a401a3793007c42f86a5c8eb537

Vulnerability Details

CWE: CWE-22: Improper Limitation of a Pathname to a Restricted Directory
Component: AsyncSSH server config reload and public-key authentication (asyncssh/config.py, asyncssh/connection.py, asyncssh/auth_keys.py, asyncssh/misc.py)
Root cause: %u in AuthorizedKeysFile is expanded from the remote username without rejecting path separators or .. segments, and the resulting path is opened without constraining it to the intended authorized-keys directory.
Security boundary violated: the configured authorized-keys directory and public-key authentication trust boundary.
Direct impact: public-key authentication succeeds using an attacker-selected authorized-keys file outside the intended directory.
Chain impact, if any: none claimed; direct authentication impact is primary.

Attack Preconditions

The AsyncSSH server uses a config or equivalent pattern where AuthorizedKeysFile contains %u, for example AuthorizedKeysFile authorized_keys/%u.
Public-key authentication is enabled.
The attacker can place or reference a readable authorized-keys-format file outside the intended directory, such as a file in a world-writable or application-writable location.
The application does not separately reject usernames containing /, \, or .. before AsyncSSH uses the username for key-file selection.

Reproduction

The run-scoped evidence contains a safe localhost proof:

Start the proof harness saved at harness_app.py
Run exploit_proof.py through run_proof.sh
The harness creates sshd_config with AuthorizedKeysFile authorized_keys/%u, writes the attacker's public key to a file outside authorized_keys/, starts a real AsyncSSH server, and attempts two SSH logins.
Expected result: the normal username victim fails, while the traversal username authenticates with the same attacker key.

Observed proof output:

[CONTROL] username=victim success=False
[ATTACK] username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub success=True
[ATTACK] output=AUTH_BYPASS_SUCCESS username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub
PASS: traversal username authenticated with attacker-controlled authorized_keys file

Severity

6.9 (Medium)


                  
                    CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P

Impacted products

Name	purl
asyncssh	pkg:pypi/asyncssh

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "asyncssh",
        "purl": "pkg:pypi/asyncssh"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.22.0"
            },
            {
              "fixed": "2.23.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.22.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45309",
    "GHSA-g794-3fmp-753h"
  ],
  "details": "## Summary\nAsyncSSH 2.22.0 expands the OpenSSH-compatible `AuthorizedKeysFile` `%u` token with the raw SSH username during pre-authentication server config reload. A server configured with a documented per-user key pattern such as `AuthorizedKeysFile authorized_keys/%u` can be made to read an authorized-keys file outside the intended directory when the SSH username contains path traversal segments. If the attacker can place or reference a readable authorized-keys-format file containing their public key, the attacker can authenticate over SSH as the traversal username.\n\n## Affected Product\n- Package: asyncssh\n- Ecosystem: pip\n- Affected versions: confirmed on 2.22.0; exact lower bound not finalized\n- Tested version: 2.22.0\n- Audit commit/tag: tag `v2.22.0`, commit `af5a81e669633d83d535163f93b6bf3f957c9238`\n- PyPI sdist SHA256: `c3ce72b01be4f97b40e62844dd384227e5ff5a401a3793007c42f86a5c8eb537`\n\n## Vulnerability Details\n- CWE: CWE-22: Improper Limitation of a Pathname to a Restricted Directory\n- Component: AsyncSSH server config reload and public-key authentication (`asyncssh/config.py`, `asyncssh/connection.py`, `asyncssh/auth_keys.py`, `asyncssh/misc.py`)\n- Root cause: `%u` in `AuthorizedKeysFile` is expanded from the remote username without rejecting path separators or `..` segments, and the resulting path is opened without constraining it to the intended authorized-keys directory.\n- Security boundary violated: the configured authorized-keys directory and public-key authentication trust boundary.\n- Direct impact: public-key authentication succeeds using an attacker-selected authorized-keys file outside the intended directory.\n- Chain impact, if any: none claimed; direct authentication impact is primary.\n\n## Attack Preconditions\n- The AsyncSSH server uses a config or equivalent pattern where `AuthorizedKeysFile` contains `%u`, for example `AuthorizedKeysFile authorized_keys/%u`.\n- Public-key authentication is enabled.\n- The attacker can place or reference a readable authorized-keys-format file outside the intended directory, such as a file in a world-writable or application-writable location.\n- The application does not separately reject usernames containing `/`, `\\`, or `..` before AsyncSSH uses the username for key-file selection.\n\n## Reproduction\nThe run-scoped evidence contains a safe localhost proof:\n\n1. Start the proof harness saved at \n[harness_app.py](https://github.com/user-attachments/files/27232526/harness_app.py)\n\n2. Run \n[exploit_proof.py](https://github.com/user-attachments/files/27232538/exploit_proof.py)\nthrough \n[run_proof.sh](https://github.com/user-attachments/files/27232545/run_proof.sh)\n\n3. The harness creates `sshd_config` with `AuthorizedKeysFile authorized_keys/%u`, writes the attacker\u0027s public key to a file outside `authorized_keys/`, starts a real AsyncSSH server, and attempts two SSH logins.\n4. Expected result: the normal username `victim` fails, while the traversal username authenticates with the same attacker key.\n\nObserved proof output:\n\n```text\n[CONTROL] username=victim success=False\n[ATTACK] username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub success=True\n[ATTACK] output=AUTH_BYPASS_SUCCESS username=../../../asyncssh-proof-exploit-proof-8b2bd23daeeb.pub\nPASS: traversal username authenticated with attacker-controlled authorized_keys file\n```",
  "id": "PYSEC-2026-2384",
  "modified": "2026-07-13T15:19:12.785321Z",
  "published": "2026-07-13T15:19:12.785321Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ronf/asyncssh/security/advisories/GHSA-g794-3fmp-753h"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ronf/asyncssh"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/asyncssh"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-g794-3fmp-753h"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45309"
    }
  ],
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "AsyncSSH `AuthorizedKeysFile %u` path traversal allows attacker-selected authorized keys to authenticate a traversal username"
}

ubuntu-cve-2026-45309

Vulnerability from osv_ubuntu

Published

2026-07-10 00:00

Modified

2026-07-10 00:00

Summary

Details

[Unknown description]

Severity

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-45309	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-45309	REPORT
	https://github.com/advisories/GHSA-g794-3fmp-753h	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-asyncssh",
            "binary_version": "1.3.0-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "python-asyncssh",
        "purl": "pkg:deb/ubuntu/python-asyncssh@1.3.0-1?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.2.0-1",
        "1.2.1-1",
        "1.3.0-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-asyncssh",
            "binary_version": "1.11.1-1ubuntu0.1~esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "python-asyncssh",
        "purl": "pkg:deb/ubuntu/python-asyncssh@1.11.1-1ubuntu0.1~esm2?arch=source\u0026distro=esm-apps/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.8.1-2",
        "1.11.0-2",
        "1.11.1-1",
        "1.11.1-1ubuntu0.1~esm1",
        "1.11.1-1ubuntu0.1~esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-asyncssh",
            "binary_version": "1.12.2-1ubuntu0.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "python-asyncssh",
        "purl": "pkg:deb/ubuntu/python-asyncssh@1.12.2-1ubuntu0.2?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.12.2-1",
        "1.12.2-1ubuntu0.1",
        "1.12.2-1ubuntu0.2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-asyncssh",
            "binary_version": "2.5.0-1ubuntu0.1+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:22.04:LTS",
        "name": "python-asyncssh",
        "purl": "pkg:deb/ubuntu/python-asyncssh@2.5.0-1ubuntu0.1+esm1?arch=source\u0026distro=esm-apps/jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.5.0-1",
        "2.5.0-1ubuntu0.1~esm1",
        "2.5.0-1ubuntu0.1",
        "2.5.0-1ubuntu0.1+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-asyncssh",
            "binary_version": "2.10.1-2ubuntu0.1+esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "python-asyncssh",
        "purl": "pkg:deb/ubuntu/python-asyncssh@2.10.1-2ubuntu0.1+esm1?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.10.1-2",
        "2.10.1-2ubuntu0.1",
        "2.10.1-2ubuntu0.1+esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-asyncssh",
            "binary_version": "2.21.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "python-asyncssh",
        "purl": "pkg:deb/ubuntu/python-asyncssh@2.21.1-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.20.0-1",
        "2.21.1-1"
      ]
    }
  ],
  "aliases": [],
  "details": "[Unknown description]",
  "id": "UBUNTU-CVE-2026-45309",
  "modified": "2026-07-10T00:00:00Z",
  "published": "2026-07-10T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-45309"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-45309"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/advisories/GHSA-g794-3fmp-753h"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-45309"
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-45309 (GCVE-0-2026-45309)

GHSA-G794-3FMP-753H

Summary

Affected Product

Vulnerability Details

Attack Preconditions

Reproduction

PYSEC-2026-2384

Summary

Affected Product

Vulnerability Details

Attack Preconditions

Reproduction

ubuntu-cve-2026-45309

Vulnerability from osv_ubuntu

Tags

Sightings

Nomenclature