VulnerabilityDeferred
CVE-2026-0865
User-controlled header names and values containing newlines can allow injecting HTTP headers.
MEDIUM 5.9EPSS 0.49%
Does this matter?
Lower severity and a low EPSS score (0.49%). Track it; it rarely justifies an emergency change on its own.
Description
User-controlled header names and values containing newlines can allow injecting HTTP headers.
- CVSS 4.0
- 5.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.49% probability · 41th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-74
- Source
- cna@python.org
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/security-announce@python.org/thread/BJ6QPHNSHJTS3A7CFV6IBMCAP2DWRVNT/
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.