CVE-2026-34993: Aiohttp AIOHTTP Is Vulnerable To Deserialization Vulnerability

MODERATE
Advisory Identifier: GHSA-jg22-mg44-37j8
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CVSS 6.4
CWE-502
Published
Advisory Summary

CVE-2026-34993 is a MODERATE (CVSS 6.4) aiohttp is vulnerable to deserialization vulnerability (CWE-502: Deserialization of Untrusted Data) affecting Aiohttp libraries in the PyPI ecosystem. The issue involves aiohttp is vulnerable to deserialization of untrusted data. Remediation is available by upgrading affected packages to version 3.14.0.

CVE-2026-34993 at a Glance

CVE Identifier CVE-2026-34993
GHSA Identifier GHSA-jg22-mg44-37j8
Severity MODERATE
CVSS v3.1 Base Score 6.4
CWE Classification CWE-502: Deserialization of Untrusted Data
Affected Product Aiohttp
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.4

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:C/C:L/I:H/A:L).

Attack Vector Local (AV:L)
Attack Complexity High (AC:H)
Privileges Required High (PR:H)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2026-34993

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: 3.14.0 
pip install aiohttp>=3.14.0
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-2026-34993, 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 3.14.0), 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-502: Deserialization of Untrusted Data, where the product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. 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 Using ``CookieJar.load()`` with untrusted input may allow arbitrary code execution. ### Impact Most applications using this function will be doing so with the user's own data, so this is unlikely to affect many applications. ### Workaround If an application does allow attacker controlled files to be loaded, a workaround on older releases would be to sanitise the files before loading. ----- Patch: https://github.com/aio-libs/aiohttp/commit/dcf40f30637e8752c76781cf6703b5a236749a00

CVE-2026-34993 Affected Aiohttp Versions

1 component(s)
Fixed Versions:
3.14.0
Product / Package Ecosystem Affected Versions Fixed Version
aiohttp
pypi/aiohttp
PyPI
< 3.14.0
3.14.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-jg22-mg44-37j8
NVD — CVE-2026-34993 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34993
Security Fix Commit FIX COMMIT
https://github.com/aio-libs/aiohttp/commit/dcf40f30637e8752c76781cf6703b5a236749a00
Aiohttp Source Repository REPOSITORY
https://github.com/aio-libs/aiohttp

Frequently Asked Questions

What is CVE-2026-34993?
CVE-2026-34993 is a security vulnerability in Aiohttp involving AIOHTTP is Vulnerable to Deserialization of Untrusted Data under CWE-502: Deserialization of Untrusted Data.
Which Aiohttp versions are affected?
Affected versions include releases prior to 3.14.0 across affected packages: aiohttp.
What version fixes CVE-2026-34993?
Upgrading to 3.14.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is aiohttp affected?
Yes, aiohttp is affected in releases prior to 3.14.0. Upgrade your dependency to 3.14.0 or later.
What is the CVSS score of CVE-2026-34993?
CVE-2026-34993 has a CVSS v3.1 base score of 6.4 (MODERATE) with vector string CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:C/C:L/I:H/A:L.
What CWE is associated with CVE-2026-34993?
CVE-2026-34993 is classified under CWE-502: Deserialization of Untrusted Data (The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.).
How can I check PyPI dependencies for CVE-2026-34993?
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-jg22-mg44-37j8",
  "modified" : "2026-06-03T20:56:54Z",
  "published" : "2026-06-03T20:56:54Z",
  "aliases" : [ "CVE-2026-34993" ],
  "summary" : "AIOHTTP is Vulnerable to Deserialization of Untrusted Data",
  "details" : "### Summary\n\nUsing ``CookieJar.load()`` with untrusted input may allow arbitrary code execution.\n\n### Impact\n\nMost applications using this function will be doing so with the user's own data, so this is unlikely to affect many applications.\n\n### Workaround\n\nIf an application does allow attacker controlled files to be loaded, a workaround on older releases would be to sanitise the files before loading.\n\n-----\n\nPatch: https://github.com/aio-libs/aiohttp/commit/dcf40f30637e8752c76781cf6703b5a236749a00",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:C/C:L/I:H/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "aiohttp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.14.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/security/advisories/GHSA-jg22-mg44-37j8"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34993"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/commit/dcf40f30637e8752c76781cf6703b5a236749a00"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/aio-libs/aiohttp"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-03T20:56:54Z",
    "nvd_published_at" : "2026-06-02T20:16:34Z"
  }
}