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
EPSS: 0.006 (43.3th percentile) — read the EPSS interpretation.
Affected products
- Python Software Foundation Cpython — versions 0, 3.11.0, 3.12.0
Weakness classification (CWE)
References
- cna@python.org (patch)
- cna@python.org (issue-tracking)
- cna@python.org (related)
- cna@python.org (vendor-advisory)
- cna@python.org (patch)
- cna@python.org (patch)
- cna@python.org (patch)
- cna@python.org (patch)
- cna@python.org (patch)
- cna@python.org (patch)