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Vulnerabilities

Security fix · CVE-2026-54279

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

Published Jun 15, 2026 · catalog updated Nov 3, 2026 · aiohttp: Host-Only Cookies Become

Last checked Nov 4, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-54279. EPSS is 0.49%. Act only if a listed version of aiohttp: Host-Only Cookies Become is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (aiohttp: Host-Only Cookies Become).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.49%
Remediation
Advisory link
Affected products
PyPI aiohttp

### Summary Host-only cookies that are saved with lose their host-only status. ### Impact Host-only cookies that have been loaded from disk may get sent to subdomains that previously should have been disallowed. ----- Patch: https://github.com/aio-libs/aiohttp/commit/a329a7aacad5284f087af36103aff778746da0f2

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • PyPI aiohttp0 → 3.14.1

How to fix CVE-2026-54279

  • Upgrade

    CVE-2026-54279 lists a fix boundary at 3.14.1. Compare the installed build with that boundary before you change production.

  • Version check

    Fixed in 3.14.1

  • Advisory

    Open the cve_org record and follow its fix.

  • Official advisories

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-54279. EPSS is 0.49%. Act only if a listed version of aiohttp: Host-Only Cookies Become is installed.

Which versions are affected?

Compare what you have installed with 0 → 3.14.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-665. EPSS 0.49%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 15, 2026 · PyPA Advisory Database

    Detected

    ### Summary Host-only cookies that are saved with lose their host-only status. ### Impact Host-only cookies that have been loaded from disk may get sent to subdomains that previously should have been disallowed. ----- Patch: https://github.com/aio-libs/aiohttp/commit/a329a7aacad5284f087af36103aff778746da0f2

  2. Nov 3, 2026 · PyPA Advisory Database

    Fix available

    aiohttp fixed in 3.14.1

  3. Nov 3, 2026 · PyPA Advisory Database

    Fix available

    aiohttp fixed in 3.14.1

  4. Nov 3, 2026 · PyPA Advisory Database

    Updated

    ### Summary Host-only cookies that are saved with lose their host-only status. ### Impact Host-only cookies that have been loaded from disk may get sent to subdomains that previously should have been disallowed. ----- Patch: https://github.com/aio-libs/aiohttp/commit/a329a7aacad5284f087af36103aff778746da0f2

Sources

References

Freshness

Last verified in this catalog Nov 4, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 4, 2026
  • PyPA Advisory DatabaseNov 4, 2026