Use-After-Free in CPython (CVE-2025-4516)
Summary
Vulnerability in CPython (CVE-2025-4516). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
There is an issue in CPython when using bytes.decode("unicode_escape", error="ignore|replace"). If you are not using the "unicode_escape" encoding or an error handler your usage is not affected. To work-around this issue you may stop using the error= handler and instead wrap the bytes.decode() call in a try-except catching the DecodeError.
Source: NIST National Vulnerability Database NVD
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2025-4516 has been found in CPython.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CPython CVE-2025-4516" on the vendor's site.
CVE-2025-4516 (CPython) — CWE-416
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Use-after-free (CWE-416) exists in CPython.
Check the vendor advisory for the affected versions of CPython.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'CPython' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'CPython' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
CPythonを grep し、稼働しているサービス・バージョンを把握する。 -
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Alpine Linux ALPINE-CVE-2025-4516 python3 Fixed in: 3.11.12-r1
- Debian DEBIAN-CVE-2025-4516 python3.11 Fixed in: 3.11.2-6+deb12u7
- Ubuntu UBUNTU-CVE-2025-4516 python3.6 Fixed in: 3.6.9-1~18.04ubuntu1.13+esm5
References
- advisory mail.python.org
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- patch github.com
- patch github.com
- patch github.com
- patch github.com
- patch github.com
- patch github.com
- patch github.com
- patch github.com
- report github.com
- web openwall.com
- web openwall.com