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Advisory record · GHSA-9548-qrrj-x5pj

AIOHTTP is vulnerable to HTTP Request/Response Smuggling through incorrect parsing of chunked trailer sections

CVSS 1.7 LowEPSS 0.0036 · 29th percentile

Published by the GitHub Advisory Database at 14 Jul 2025, 19:33 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
aiohttpPyPI<3.12.143.12.14
Identifiers
GHSA-9548-qrrj-x5pj · CVE-2025-53643 · PYSEC-2026-1104
Weakness (CWE)
CWE-444
Tags
Published
14 Jul 2025
Updated
10 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Affected: aiohttp versions before 3.12.14. The pure Python HTTP parser does not parse trailer sections of chunked requests, which enables request smuggling. This applies only when aiohttp runs without its C extensions or with AIOHTTP_NO_EXTENSIONS enabled. An attacker could use smuggling to bypass firewall or proxy protections. Upgrade to aiohttp 3.12.14 or later.

Written 5 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
1.7 Low 4.0 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0036, the 29th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:34 UTC First seen by agentprime
  2. 31 Oct 2026, 14:34 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.