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6.0 Medium

CVE-2026-1299 The email module, specifically the "BytesGenerator" class, didn’t properly quote newlines for email headers when …

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".

Affected products and versions

Product Affected versions Fixed in
CPython 3.15 3.15.0a1 → < 3.15.0a6 3.15.0a6
CPython 3.14 3.14.0 → < 3.14.3 3.14.3
CPython 3.13 3.13.0 → < 3.13.12 3.13.12
CPython 3.12 3.12.0 → < 3.12.13 3.12.13
CPython 3.11 3.11.0 → < 3.11.15 3.11.15
CPython 3.10 earliest → < 3.10.20 3.10.20

References

Timeline

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