# CVE-2026-124249: `http.cookiejar` applies expired `Set-Cookie` to cookie store before policy validation


- **Severity:** Medium 6.3 (`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`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 9 Nov 2026
- **Updated:** 12 Nov 2026
- **Also known as:** AZL-112910, AZL-112916, GHSA-chc2-vx2q-cwqf, UBUNTU-CVE-2026-124249

## What is CVE-2026-124249?

CVE-2026-124249 is a medium-severity vulnerability in CPython, published on 9 Nov 2026. 

### Official description

http.cookiejar.CookieJar deleted a stored cookie when a response carried an
already expired Set-Cookie header for it, using the Domain and Path
attributes from the header without consulting the cookie policy. A server
could therefore delete cookies belonging to other domains from a shared
cookie jar, such as the one used by urllib's HTTPCookieProcessor. The fix
consults the cookie policy before an expired cookie may delete an existing
one, as required by RFC 6265 section 5.3.

Weakness: CWE-346 (Origin Validation Error)

## Which versions are affected by CVE-2026-124249?


## How do I fix CVE-2026-124249?

No fix has been published for CVE-2026-124249 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-124249 being exploited?

There is no known exploitation of CVE-2026-124249 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-124249 and fix it if it is affected.

What it is: CVE-2026-124249 is a medium-severity vulnerability in CPython, published on 9 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-124249 in the wild and no public exploit code.

Affected product: CPython. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-124249/ (Markdown: https://insights.sbomify.com/CVE-2026-124249/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-124249
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-124249
- OSV: https://osv.dev/vulnerability/CVE-2026-124249

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-124249/
Summaries are generated and may contain mistakes; the official description above is the record.