high CVSS 7.5

CVE-2026-54279·Python vulnerability

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.1, host-only cookies that are saved with CookieJar.save() and then restored later with CookieJar.load() lose their host-only status. This vulnerability is fixed in 3.14.1.

Severity
high
Software
Python
Fixed in
3.14.1
Published
2026-06-22

Affected versions

Until: 3.14.1

Fixed in: 3.14.1

How to fix this CVE

Update Python's aiohttp library to version 3.14.1 or later to resolve a cookie handling vulnerability that causes host-only cookies to lose their security classification after being saved and restored. This flaw could allow cookies to be sent to unintended domains if not patched. Prioritize updating aiohttp in any environment where cookie-based authentication or session management is critical.

sudo dnf update python3-aiohttp

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed aiohttp version: python3 -c "import aiohttp; print(aiohttp.__version__)"
  2. Verify if aiohttp is in use by searching application requirements: grep -r "aiohttp" /path/to/app/requirements.txt /path/to/app/setup.py 2>/dev/null
  3. Search application logs for cookie operations that may have been affected: grep -i "cookie" /var/log/application.log | head -20
  4. Confirm the patch is applied by re-running the version check and verifying it reports 3.14.1 or higher

FAQ

What is CVE-2026-54279?

CVE-2026-54279 is a vulnerability in aiohttp where host-only cookies that are persisted to disk and later reloaded lose their host-only flag, potentially allowing them to be transmitted to unintended domains. This occurs in the CookieJar save/load cycle.

Is CVE-2026-54279 being actively exploited?

No, this vulnerability is not listed on CISA's KEV catalog and no public exploits are currently available.

What versions of aiohttp are affected by CVE-2026-54279?

All versions of aiohttp prior to 3.14.1 are affected by this vulnerability.

How do I check if my server is vulnerable to CVE-2026-54279?

Run: python3 -c "import aiohttp; v = tuple(map(int, aiohttp.__version__.split('.')[:3])); print('Vulnerable' if v < (3, 14, 1) else 'Patched')"

Does Defensia detect CVE-2026-54279?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If aiohttp is installed on a monitored server, CVE-2026-54279 will appear in your dashboard with remediation steps.

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References

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