Low

AIOHTTP's unicode processing of header values could cause parsing discrepancies

  • Disclosed: 05.01.2026
  • Updated: 11.10.2026 15:17

Summary

The Python HTTP parser may allow a request smuggling attack with the presence of non-ASCII characters.

Impact

If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTP_NO_EXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.


Patch: https://github.com/aio-libs/aiohttp/commit/32677f2adfd907420c078dda6b79225c6f4ebce0

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Python (PyPI) aiohttp < 3.13.3 3.13.3

References

CVSS score -
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U
Weakness (CWE)
CWE-444
Platform
Python (PyPI)
Package
aiohttp
Disclosed
05.01.2026
Updated
11.10.2026 15:17

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2026-1099 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-69f9-5gxw-wvc2 - CC BY 4.0

Vulnerability history: aiohttp

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (55) in the archive
Total entries
55
First → latest
02.2021 10.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 7
  • Medium 29
  • Low 19

Disclosures per year

  1. 2021: 1
  2. 2022: 0
  3. 2023: 6
  4. 2024: 7
  5. 2025: 1
  6. 2026: 40
Severity:
  1. High CVE-2026-111066 >= 2.0.0, < 3.14.4 3.14.4
  2. High CVE-2026-111064 < 3.14.4 3.14.4
  3. AIOHTTP's unicode processing of header values could cause parsing discrepancies this entry
    Low CVE-2025-69224 < 3.13.3 3.13.3
  4. High · 5.9 CVE-2024-23334 >= 1.0.5, < 3.9.2 3.9.2

Know which vulnerabilities affect your application

With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.

Connect your application
DockRay newsletter

Application security in your inbox

Important vulnerabilities, actionable guidance and practical advice for your applications. Choose your technologies and follow what matters to your project.

  • A daily digest of new vulnerabilities, critical ones included.
  • Notifications about important updates.
  • Practical advice on application security and monitoring.

Leave empty to receive updates for every technology.

Free to subscribe. Unsubscribe with one click in any email.