Email Module Vulnerability in Python's BytesGenerator Class
CVE-2026-1299

6MEDIUM

Key Information:

Vendor

Python Software Foundation

Status
Cpython
Vendor
CVE Published:
23 January 2026

What is CVE-2026-1299?

The email module in Python contains a vulnerability within the BytesGenerator class that fails to adequately quote newlines when serializing email headers. This oversight may lead to header injection vulnerabilities, particularly in scenarios where 'LiteralHeader' is used, which disregards standard email folding rules. The revised behavior introduced in recent updates will now reject headers that are incorrectly formatted, enhancing overall security.

Affected Version(s)

CPython 0 < 3.10.20

CPython 3.11.0 < 3.11.15

CPython 3.12.0 < 3.12.13

References

https://github.com/python/cpython/pull/144126
patch
https://github.com/python/cpython/issues/144125
issue-tracking
https://cve.org/CVERecord?id=CVE-2024-6923
related

CVSS V4

Score:
6
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.