Vulnerability in Python Software Foundation Cpython
CVE-2026-1299
The email module, specifically the "BytesGenerator" class, didn’t properly quote newlines for email headers when serializing an email message allowing for header injection when an email is serialized. This is only applicable if using "LiteralHeader" writing headers that don't respect email folding rules, the new behavior will reject the incorrectly folded headers in "BytesGenerator".
Vulnerability class: CRLF Injection
Published · last modified .
EPSS exploit prediction
EPSS: 0.006 (45.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 45.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.000
Affected products
- Python Software Foundation Cpython — versions 0, 3.11.0, 3.12.0
Weakness classification (CWE)
References
- github.com/python/cpython/pull/144126 (patch)
- github.com/python/cpython/issues/144125 (issue-tracking)
- cve.org/CVERecord (related)
- mail.python.org/archives/list/security-announce@python.org/thread/6ZZULGALJTITE… (vendor-advisory)
- github.com/python/cpython/commit/052e55e7d44718fe46cbba0ca995cb8fcc359413 (patch)
- github.com/python/cpython/commit/0a925ab591c45d6638f37b5e57796f36fa0e56d8 (patch)
- github.com/python/cpython/commit/7877fe424415bc4a13045e62a90a7277413d8cb9 (patch)
- github.com/python/cpython/commit/842ce19a0c0b58d61591e8f6a708c38db1fb94e4 (patch)
- github.com/python/cpython/commit/8cdf6204f4ae821f32993f8fc6bad0d318f95f36 (patch)
- github.com/python/cpython/commit/e417f05ad77a4c30ddc07f99e90fc0cef43e831a (patch)