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CVE-2026-0865
User-controlled header names and values containing newlines can allow injecting HTTP headers.
AI summary snake-internal / snake-template-v1
A weakness called CVE-2026-0865 was discovered in User-controlled header names.
Severity is Info. Low severity or not yet rated.
What you should do: update the affected software to the latest version. If unsure, ask your IT team or search the vendor's site for "User-controlled header names CVE-2026-0865".
CVE-2026-0865 (User-controlled header names). Severity: Info.
Response plan:
1. Check the vendor advisory for affected versions and the patched release.
2. If a vulnerable version is running in production, schedule maintenance (urgency from KEV/CVSS).
3. If no patch yet, mitigate via WAF rule, disabling the affected feature, etc.
4. Monitor logs / SIEM for known IOC and PoC signatures of this CVE.
PoCs and fix commits: see the 'References' section, MITRE, and NVD.
❓ What is the problem
A weakness (CVE-2026-0865) in User-controlled header names. A serious software flaw has been identified.
📍 Affected scope
Target versions of User-controlled header names (see vendor advisory). If running in production, identify exposure immediately.
🔥 Severity
Severity: Info. Low severity or not yet rated.
🔧 How to fix
Update to the patched release as listed in the vendor advisory.
🛡️ Workaround
If a patch is not yet available, consider disabling the affected feature, applying WAF rules, blocking via network ACLs, or isolating the vulnerable version.
🔍 Detection
Check version information, scan dependencies via SBOM, and monitor SIEM for IOC and PoC signatures related to this CVE.
References
- patch https://github.com/python/cpython/commit/23e3c0ae867cca0130e441e776c9955b9027c510
- patch https://github.com/python/cpython/commit/83ecd18779f286d872f68bfce175651e407d9fff
- patch https://github.com/python/cpython/commit/286e3ac39984fe85a17f4ab39c64d382137aae5f
- patch https://github.com/python/cpython/commit/2f840249550e082dc351743f474ba56da10478d2
- patch https://github.com/python/cpython/commit/bfba660085767f8c2d582134e9d511a85eda04cf
- patch https://github.com/python/cpython/commit/c592227ffb48679af9845a45dbb0875d975bb219
- patch https://github.com/python/cpython/commit/e4846a93ac07a8ae9aa18203af0dd13d6e7a6995
- patch https://github.com/python/cpython/commit/f7fceed79ca1bceae8dbe5ba5bc8928564da7211
- patch https://github.com/python/cpython/pull/143917
- patch https://github.com/python/cpython/commit/22e4d55285cee52bc4dbe061324e5f30bd4dee58
- patch https://github.com/python/cpython/commit/4802b96a2cde58570c24c13ef3289490980961c5
- patch https://github.com/python/cpython/commit/66da7bf6fe7b81e3ecc9c0a25bd47d4616c8d1a6
- patch https://github.com/python/cpython/commit/8bb044d29310bb05d15086cdaa8bf64867d61a97
- report https://github.com/python/cpython/issues/143916
- web https://mail.python.org/archives/list/security-announce@python.org/thread/BJ6QPHNSHJTS3A7CFV6IBMCAP2DWRVNT/