CVE-2026-0865
CVE-2026-0865 is a medium-severity vulnerability with a CVSS 4.0 base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-74.
Key facts
- Severity: Medium (CVSS 4.0 base score 5.9)
- EPSS exploit prediction: 0% (37th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-3520
- Weakness: CWE-74
- Published:
- Last modified:
Description
User-controlled header names and values containing newlines can allow injecting HTTP headers.
Frequently asked questions
- What is CVE-2026-0865?
- User-controlled header names and values containing newlines can allow injecting HTTP headers.
- How severe is CVE-2026-0865?
- CVE-2026-0865 has a CVSS 4.0 base score of 5.9, rated medium severity.
- Is CVE-2026-0865 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-0865?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-0865 have an EU (EUVD) identifier?
- Yes. CVE-2026-0865 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-3520.
- When was CVE-2026-0865 published?
- CVE-2026-0865 was published on 2026-01-20 and last updated on 2026-06-17.
References
- https://github.com/python/cpython/commit/22e4d55285cee52bc4dbe061324e5f30bd4dee58
- https://github.com/python/cpython/commit/23e3c0ae867cca0130e441e776c9955b9027c510
- https://github.com/python/cpython/commit/286e3ac39984fe85a17f4ab39c64d382137aae5f
- https://github.com/python/cpython/commit/2f840249550e082dc351743f474ba56da10478d2
- https://github.com/python/cpython/commit/4802b96a2cde58570c24c13ef3289490980961c5
- https://github.com/python/cpython/commit/66da7bf6fe7b81e3ecc9c0a25bd47d4616c8d1a6
- https://github.com/python/cpython/commit/83ecd18779f286d872f68bfce175651e407d9fff
- https://github.com/python/cpython/commit/8bb044d29310bb05d15086cdaa8bf64867d61a97
- https://github.com/python/cpython/commit/bfba660085767f8c2d582134e9d511a85eda04cf
- https://github.com/python/cpython/commit/c592227ffb48679af9845a45dbb0875d975bb219
- https://github.com/python/cpython/commit/e4846a93ac07a8ae9aa18203af0dd13d6e7a6995
- https://github.com/python/cpython/commit/f7fceed79ca1bceae8dbe5ba5bc8928564da7211
- https://github.com/python/cpython/issues/143916
- https://github.com/python/cpython/pull/143917
- https://mail.python.org/archives/list/[email protected]/thread/BJ6QPHNSHJTS3A7CFV6IBMCAP2DWRVNT/
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