CVE-2026-34515: Aiohttp Remote Code Execution Vulnerability

MODERATE
Advisory Identifier: GHSA-p998-jp59-783m
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CWE-36 CWE-918
Published
Advisory Summary

CVE-2026-34515 is a MODERATE remote code execution vulnerability (CWE-36: Absolute Path Traversal) affecting Aiohttp libraries in the PyPI ecosystem. The issue involves aiohttp affected by unc ssrf/ntlmv2 credential theft/local file read in static resource handler on windows. Remediation is available by upgrading affected packages to version 3.13.4.

CVE-2026-34515 at a Glance

CVE Identifier CVE-2026-34515
GHSA Identifier GHSA-p998-jp59-783m
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-36: Absolute Path Traversal
Affected Product Aiohttp
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix CVE-2026-34515

To remediate this vulnerability, upgrade all affected Aiohttp dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

aiohttp fixed: 3.13.4 
pip install aiohttp>=3.13.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show aiohttp

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-34515, inspect your installed packages using pip:

pip show aiohttp

Analyze the terminal output to locate any version of Aiohttp in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.13.4), your application is affected.

Note: The pip show aiohttp command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-36: Absolute Path Traversal, where the product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize absolute path sequences such as "/abs/path" that can resolve to a location that is outside of that directory. In Aiohttp, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary On Windows the static resource handler may expose information about a NTLMv2 remote path. ### Impact If an application is running on Windows, and using aiohttp's static resource handler (not recommended in production), then it may be possible for an attacker to extract the hash from an NTLMv2 path and then extract the user's credentials from there. ----- Patch: https://github.com/aio-libs/aiohttp/commit/0ae2aa076c84573df83fc1fdc39eec0f5862fe3d

CVE-2026-34515 Affected Aiohttp Versions

1 component(s)
Fixed Versions:
3.13.4
Product / Package Ecosystem Affected Versions Fixed Version
aiohttp
pypi/aiohttp
PyPI
< 3.13.4
3.13.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-p998-jp59-783m
NVD — CVE-2026-34515 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34515
Security Fix Commit FIX COMMIT
https://github.com/aio-libs/aiohttp/commit/0ae2aa076c84573df83fc1fdc39eec0f5862fe3d
Aiohttp Source Repository REPOSITORY
https://github.com/aio-libs/aiohttp
Aiohttp Release RELEASE
https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4

Frequently Asked Questions

What is CVE-2026-34515?
CVE-2026-34515 is a security vulnerability in Aiohttp involving AIOHTTP affected by UNC SSRF/NTLMv2 Credential Theft/Local File Read in static resource handler on Windows under CWE-36: Absolute Path Traversal.
Which Aiohttp versions are affected?
Affected versions include releases prior to 3.13.4 across affected packages: aiohttp.
What version fixes CVE-2026-34515?
Upgrading to 3.13.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is aiohttp affected?
Yes, aiohttp is affected in releases prior to 3.13.4. Upgrade your dependency to 3.13.4 or later.
What CWE is associated with CVE-2026-34515?
CVE-2026-34515 is classified under CWE-36: Absolute Path Traversal (The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize absolute path sequences such as "/abs/path" that can resolve to a location that is outside of that directory.).
How can I check PyPI dependencies for CVE-2026-34515?
Run the dependency tree command: 'pip show aiohttp'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-p998-jp59-783m",
  "modified" : "2026-04-06T16:47:09Z",
  "published" : "2026-04-01T21:26:36Z",
  "aliases" : [ "CVE-2026-34515" ],
  "summary" : "AIOHTTP affected by UNC SSRF/NTLMv2 Credential Theft/Local File Read in static resource handler on Windows",
  "details" : "### Summary\n\nOn Windows the static resource handler may expose information about a NTLMv2 remote path.\n\n### Impact\n\nIf an application is running on Windows, and using aiohttp's static resource handler (not recommended in production), then it may be possible for an attacker to extract the hash from an NTLMv2 path and then extract the user's credentials from there.\n\n-----\n\nPatch: https://github.com/aio-libs/aiohttp/commit/0ae2aa076c84573df83fc1fdc39eec0f5862fe3d",
  "severity" : [ {
    "type" : "CVSS_V4",
    "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:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "aiohttp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.13.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 3.13.3"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/security/advisories/GHSA-p998-jp59-783m"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34515"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/commit/0ae2aa076c84573df83fc1fdc39eec0f5862fe3d"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/aio-libs/aiohttp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-36", "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-01T21:26:36Z",
    "nvd_published_at" : "2026-04-01T21:16:59Z"
  }
}