CVE-2026-0865
Medium
Description
User-controlled header names and values containing newlines can allow injecting HTTP headers.
SeverityMedium
CVSS5.9
Exploit probability—
ProductCPython
PublishedJan 20, 2026
First seenJan 20, 2026
Weakness typeCWE-74Injection
How to fix
Update
- Python Software Foundation CPython3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3, 3.15.0a6 or later
Patches
- github.com/python/cpython/pull/143917
- github.com/python/cpython/commit/22e4d55285cee52bc4dbe061324e5f30bd4dee58
- github.com/python/cpython/commit/23e3c0ae867cca0130e441e776c9955b9027c510
- github.com/python/cpython/commit/4802b96a2cde58570c24c13ef3289490980961c5
- github.com/python/cpython/commit/f7fceed79ca1bceae8dbe5ba5bc8928564da7211
- github.com/python/cpython/commit/2f840249550e082dc351743f474ba56da10478d2
- github.com/python/cpython/commit/e4846a93ac07a8ae9aa18203af0dd13d6e7a6995
- github.com/python/cpython/commit/66da7bf6fe7b81e3ecc9c0a25bd47d4616c8d1a6
- github.com/python/cpython/commit/83ecd18779f286d872f68bfce175651e407d9fff
- github.com/python/cpython/commit/bfba660085767f8c2d582134e9d511a85eda04cf
- github.com/python/cpython/commit/286e3ac39984fe85a17f4ab39c64d382137aae5f
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Python Software Foundation CPython | v < 3.10.20, 3.11.0 ≤ v < 3.11.15, 3.12.0 ≤ v < 3.12.13, 3.13.0 ≤ v < 3.13.12, 3.14.0 ≤ v < 3.14.3, 3.15.0a1 ≤ v < 3.15.0a6 | 3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3, 3.15.0a6 |
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