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Advisory record · GHSA-2fqr-mr3j-6wp8

aiohttp: Host-Only Cookies Become Domain Cookies After CookieJar Persistence

CVSS 1.3 LowEPSS 0.0049 · 42nd percentile

Published by the GitHub Advisory Database at 15 Jun 2026, 20:08 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
aiohttpPyPI<3.14.13.14.1
Identifiers
GHSA-2fqr-mr3j-6wp8 · CVE-2026-54279 · PYSEC-2026-2112
Weakness (CWE)
CWE-665
Tags
Published
15 Jun 2026
Updated
3 Nov 2026

Machine-written summary

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

aiohttp versions before 3.14.1 lose host-only status for cookies that are saved with CookieJar.save() and later restored with CookieJar.load(). As a result, a host-only cookie restored from disk may be sent to subdomains it should not reach. Upgrade to aiohttp 3.14.1 or later. The source gives few details on the attacker's position required for exploitation.

Written 1 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
1.3 Low 4.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N/E:U CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0049, the 42nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 15 Jun 2026, 20:08 UTC Confirmed by GitHub Advisory Database
  2. 31 Oct 2026, 14:11 UTC First seen by agentprime
  3. 31 Oct 2026, 14:11 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.