CVE-2026-22815: Aiohttp Aiohttp Allows Unlimited Trailer Headers, Vulnerability

MODERATE
Advisory Identifier: GHSA-w2fm-2cpv-w7v5
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CWE-400 CWE-770
Published
Advisory Summary

CVE-2026-22815 is a MODERATE aiohttp allows unlimited trailer headers, vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Aiohttp libraries in the PyPI ecosystem. The issue involves aiohttp allows unlimited trailer headers, leading to possible uncapped memory usage. Remediation is available by upgrading affected packages to version 3.13.4.

CVE-2026-22815 at a Glance

CVE Identifier CVE-2026-22815
GHSA Identifier GHSA-w2fm-2cpv-w7v5
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Aiohttp
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix CVE-2026-22815

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-2026-22815, 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-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. 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 Insufficient restrictions in header/trailer handling could cause uncapped memory usage. ### Impact An application could cause memory exhaustion when receiving an attacker controlled request or response. A vulnerable web application could mitigate these risks with a typical reverse proxy configuration. ----- Patch: https://github.com/aio-libs/aiohttp/commit/0c2e9da51126238a421568eb7c5b53e5b5d17b36

CVE-2026-22815 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-w2fm-2cpv-w7v5
NVD — CVE-2026-22815 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-22815
Security Fix Commit FIX COMMIT
https://github.com/aio-libs/aiohttp/commit/0c2e9da51126238a421568eb7c5b53e5b5d17b36
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-2026-22815?
CVE-2026-22815 is a security vulnerability in Aiohttp involving aiohttp allows unlimited trailer headers, leading to possible uncapped memory usage under CWE-400: Uncontrolled Resource Consumption.
Which Aiohttp versions are affected?
Affected versions include releases prior to 3.13.4 across affected packages: aiohttp.
What version fixes CVE-2026-22815?
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-2026-22815?
CVE-2026-22815 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check PyPI dependencies for CVE-2026-22815?
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-w2fm-2cpv-w7v5",
  "modified" : "2026-04-06T16:46:33Z",
  "published" : "2026-04-01T19:45:17Z",
  "aliases" : [ "CVE-2026-22815" ],
  "summary" : "aiohttp allows unlimited trailer headers, leading to possible uncapped memory usage",
  "details" : "### Summary\n\nInsufficient restrictions in header/trailer handling could cause uncapped memory usage.\n\n### Impact\n\nAn application could cause memory exhaustion when receiving an attacker controlled request or response. A vulnerable web application could mitigate these risks with a typical reverse proxy configuration.\n\n-----\n\nPatch: https://github.com/aio-libs/aiohttp/commit/0c2e9da51126238a421568eb7c5b53e5b5d17b36",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
  } ],
  "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-w2fm-2cpv-w7v5"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-22815"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aio-libs/aiohttp/commit/0c2e9da51126238a421568eb7c5b53e5b5d17b36"
  }, {
    "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-400", "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-01T19:45:17Z",
    "nvd_published_at" : "2026-04-01T21:16:58Z"
  }
}