CVE-2026-1299

Description

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".

How to fix CVE-2026-1299

To remediate CVE-2026-1299, upgrade the affected package to a fixed version below.

• Bitnami/libpython—upgrade to 3.10.20 or later
• —upgrade to 3.10.20 or later
• —upgrade to 3.10.20 or later
• —no fix listed
• —upgrade to 3.11.2-6+deb12u7 or later
• —upgrade to 3.13.5-2+deb13u1 or later
• —upgrade to 3.14.3-1 or later
• —upgrade to 3.9.2-1+deb11u5 or later

Is CVE-2026-1299 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (8)

• from 0, < 3.10.20, >= 3.11.0, < 3.11.15, >= 3.12.0, < 3.12.13, >= 3.13.0, < 3.13.12, >= 3.14.0, < 3.14.3
• from 0, < 3.10.20, >= 3.11.0, < 3.11.15, >= 3.12.0, < 3.12.13, >= 3.13.0, < 3.13.12, >= 3.14.0, < 3.14.3
• from 0, < 3.10.20, >= 3.11.0, < 3.11.15, >= 3.12.0, < 3.12.13, >= 3.13.0, < 3.13.12, >= 3.14.0, < 3.14.3
• from 0
• from 0, < 3.11.2-6+deb12u7
• from 0, < 3.13.5-2+deb13u1
• from 0, < 3.14.3-1
• from 0, < 3.9.2-1+deb11u5

CVSS scores

References (12)

• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-1299
• WEBcve.org/CVERecord?id=CVE-2024-6923
• WEBgithub.com/python/cpython/commit/052e55e7d44718fe46cbba0ca995cb8fcc359413
• WEBgithub.com/python/cpython/commit/0a925ab591c45d6638f37b5e57796f36fa0e56d8