CVE-2026-1299: email BytesGenerator header injection due to unquoted newlines
Python Software Foundation · CPython
Vendor fix available · Affected: Python Software Foundation CPython · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 47% of scored CVEs
DescriptionCVE.org
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".
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- Python Software Foundation · CPythonbefore 3.10.20; from 3.11.0 before 3.11.15; from 3.12.0 before 3.12.13; from 3.13.0 before 3.13.12; from 3.14.0 before 3.14.3; from 3.15.0a1 before 3.15.0a6
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Published
- January 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-1299 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.