Vulnerability · Published Jan 20, 2026 · Assigned by PSF
CVE-2026-0865wsgiref.headers.Headers allows header newline injection
Medium 5.9
In plain English
A medium-severity injection in CPython from Python Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 46% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 4.0)5.9Medium
Exploit odds (30 days)0.6%top 53.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
User-controlled header names and values containing newlines can allow injecting HTTP headers.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | platform-python | 3.6.8-73.el8_10.alma.1 | ALSA-2026:2128 |
| AlmaLinux:8 | platform-python-debug | 3.6.8-73.el8_10.alma.1 | ALSA-2026:2128 |
| AlmaLinux:8 | platform-python-devel | 3.6.8-73.el8_10.alma.1 | ALSA-2026:2128 |
| AlmaLinux:10 | python-unversioned-command | 3.12.12-3.el10_1.1 | ALSA-2026:4713 |
| AlmaLinux:9 | python-unversioned-command | 3.9.25-3.el9_7.1 | ALSA-2026:4168 |
| AlmaLinux:9 | python3 | 3.9.25-3.el9_7.1 | ALSA-2026:4168 |
| AlmaLinux:9 | python3-debug | 3.9.25-3.el9_7.1 | ALSA-2026:4168 |
| AlmaLinux:9 | python3-devel | 3.9.25-3.el9_7.1 | ALSA-2026:4168 |
| AlmaLinux:8 | python3-idle | 3.6.8-73.el8_10.alma.1 | ALSA-2026:2128 |
| AlmaLinux:9 | python3-idle | 3.9.25-3.el9_7.1 | ALSA-2026:4168 |
| AlmaLinux:8 | python3-libs | 3.6.8-73.el8_10.alma.1 | ALSA-2026:2128 |
| AlmaLinux:9 | python3-libs | 3.9.25-3.el9_7.1 | ALSA-2026:4168 |
| AlmaLinux:8 | python3-test | 3.6.8-73.el8_10.alma.1 | ALSA-2026:2128 |
| AlmaLinux:9 | python3-test | 3.9.25-3.el9_7.1 | ALSA-2026:4168 |
| AlmaLinux:8 | python3-tkinter | 3.6.8-73.el8_10.alma.1 | ALSA-2026:2128 |
| AlmaLinux:9 | python3-tkinter | 3.9.25-3.el9_7.1 | ALSA-2026:4168 |
| AlmaLinux:8 | python3.11 | 3.11.13-5.el8_10 | ALSA-2026:4473 |
| AlmaLinux:8 | python3.11-debug | 3.11.13-5.el8_10 | ALSA-2026:4473 |
| AlmaLinux:8 | python3.11-devel | 3.11.13-5.el8_10 | ALSA-2026:4473 |
| AlmaLinux:8 | python3.11-idle | 3.11.13-5.el8_10 | ALSA-2026:4473 |
| AlmaLinux:8 | python3.11-libs | 3.11.13-5.el8_10 | ALSA-2026:4473 |
| AlmaLinux:8 | python3.11-rpm-macros | 3.11.13-5.el8_10 | ALSA-2026:4473 |
| AlmaLinux:8 | python3.11-test | 3.11.13-5.el8_10 | ALSA-2026:4473 |
| AlmaLinux:8 | python3.11-tkinter | 3.11.13-5.el8_10 | ALSA-2026:4473 |
| AlmaLinux:8 | python3.12 | 3.12.12-3.el8_10 | ALSA-2026:4463 |
| AlmaLinux:8 | python3.12-debug | 3.12.12-3.el8_10 | ALSA-2026:4463 |
| AlmaLinux:8 | python3.12-devel | 3.12.12-3.el8_10 | ALSA-2026:4463 |
| AlmaLinux:8 | python3.12-idle | 3.12.12-3.el8_10 | ALSA-2026:4463 |
| AlmaLinux:8 | python3.12-libs | 3.12.12-3.el8_10 | ALSA-2026:4463 |
| AlmaLinux:8 | python3.12-rpm-macros | 3.12.12-3.el8_10 | ALSA-2026:4463 |
| AlmaLinux:8 | python3.12-test | 3.12.12-3.el8_10 | ALSA-2026:4463 |
| AlmaLinux:8 | python3.12-tkinter | 3.12.12-3.el8_10 | ALSA-2026:4463 |
| AlmaLinux:10 | python3.14 | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14 | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-debug | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-debug | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-devel | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-devel | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-freethreading | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-freethreading | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-freethreading-debug | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-freethreading-debug | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-freethreading-devel | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-freethreading-devel | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-freethreading-idle | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-freethreading-idle | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-freethreading-libs | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-freethreading-libs | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-freethreading-test | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-freethreading-test | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-freethreading-tkinter | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-freethreading-tkinter | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-idle | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-idle | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-libs | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-libs | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-test | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-test | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| AlmaLinux:10 | python3.14-tkinter | 3.14.4-2.el10_2 | ALSA-2026:19019 |
| AlmaLinux:9 | python3.14-tkinter | 3.14.4-2.el9_8 | ALSA-2026:19176 |
| Debian:12 | jython | no fix listed | DEBIAN-CVE-2026-0865 |
| Debian:13 | jython | no fix listed | DEBIAN-CVE-2026-0865 |
| Debian:14 | jython | no fix listed | DEBIAN-CVE-2026-0865 |
| Debian:12 | pypy3 | no fix listed | DEBIAN-CVE-2026-0865 |
| Debian:13 | pypy3 | no fix listed | DEBIAN-CVE-2026-0865 |
| Debian:14 | pypy3 | 7.3.21+dfsg-1 | DEBIAN-CVE-2026-0865 |
| Debian:12 | python3.11 | 3.11.2-6+deb12u7 | DEBIAN-CVE-2026-0865 |
| Debian:13 | python3.13 | 3.13.5-2+deb13u1 | DEBIAN-CVE-2026-0865 |
| Debian:14 | python3.14 | 3.14.3-1 | DEBIAN-CVE-2026-0865 |
| Rocky Linux:8 | python3 | 0:3.6.8-73.el8_10.rocky.0 | RLSA-2026:2128 |
| Rocky Linux:8 | python3.11 | 0:3.11.13-5.el8_10 | RLSA-2026:4473 |
| Rocky Linux:10 | python3.12 | 0:3.12.12-3.el10_1.1 | RLSA-2026:4713 |
| Rocky Linux:8 | python3.12 | 0:3.12.12-3.el8_10 | RLSA-2026:4463 |
| Rocky Linux:10 | python3.14 | 0:3.14.4-2.el10_2 | RLSA-2026:19019 |
| Rocky Linux:9 | python3.14 | 0:3.14.4-2.el9_8 | RLSA-2026:19176 |
| Rocky Linux:9 | python3.9 | 0:3.9.25-3.el9_7.1 | RLSA-2026:4168 |
| Ubuntu:22.04:LTS | python3.10 | 3.10.12-1~22.04.14 | UBUNTU-CVE-2026-0865 |
| Ubuntu:24.04:LTS | python3.12 | 3.12.3-1ubuntu0.11 | UBUNTU-CVE-2026-0865 |
| Ubuntu:25.10 | python3.13 | 3.13.7-1ubuntu0.3 | UBUNTU-CVE-2026-0865 |
| Ubuntu:25.10 | python3.14 | 3.14.0-1ubuntu0.2 | UBUNTU-CVE-2026-0865 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Python Software Foundation | CPython | 0 – before 3.10.203.11.0 – before 3.11.153.12.0 – before 3.12.133.13.0 – before 3.13.123.14.0 – before 3.14.33.15.0a1 – before 3.15.0a6 |
Weakness: CWE-74 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
References
- https://github.com/python/cpython/pull/143917 patch
- https://github.com/python/cpython/issues/143916 issue-tracking
- https://mail.python.org/archives/list/security-announce@python.org/thread/BJ6QPHNSHJTS3A7CFV6IBMCAP2DWRVNT/ vendor-advisory
- https://github.com/python/cpython/commit/22e4d55285cee52bc4dbe061324e5f30bd4dee58 patch
- https://github.com/python/cpython/commit/23e3c0ae867cca0130e441e776c9955b9027c510 patch
- https://github.com/python/cpython/commit/4802b96a2cde58570c24c13ef3289490980961c5 patch
- https://github.com/python/cpython/commit/f7fceed79ca1bceae8dbe5ba5bc8928564da7211 patch
- https://github.com/python/cpython/commit/2f840249550e082dc351743f474ba56da10478d2 patch
- https://github.com/python/cpython/commit/e4846a93ac07a8ae9aa18203af0dd13d6e7a6995 patch
- https://github.com/python/cpython/commit/66da7bf6fe7b81e3ecc9c0a25bd47d4616c8d1a6 patch
- https://github.com/python/cpython/commit/83ecd18779f286d872f68bfce175651e407d9fff patch
- https://github.com/python/cpython/commit/bfba660085767f8c2d582134e9d511a85eda04cf patch
- https://github.com/python/cpython/commit/286e3ac39984fe85a17f4ab39c64d382137aae5f patch
- https://github.com/python/cpython/commit/8bb044d29310bb05d15086cdaa8bf64867d61a97 patch
- https://github.com/python/cpython/commit/c592227ffb48679af9845a45dbb0875d975bb219 patch