CVE-2026-1299

email BytesGenerator header injection due to unquoted newlines

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".

Patch Available

Fix available through Seal Security.  
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Fix without upgrading

Score

Severity

Medium

Ecosystem

APT

Publish Date

January 23, 2026

Modified Date

February 13, 2026

Score Vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected Versions