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OpenAdvisories
Medium · 5.8 CVE-2026-73213 EUVD-2026-56819

Coturn: `addr_less_eq()` does a component-wise IPv6 comparison instead of a lexicographic one, letting an authenticated TURN client bypass `denied-peer-ip`/`allowed-peer-ip` IPv6 ranges (TURN-specific SSRF)

Published Aug 11, 2026 · Updated Aug 13, 2026 · Assigned by GitHub_M

Description

Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.16.0, addr_less_eq() in src/client/ns_turn_ioaddr.c uses a component-wise comparison for native IPv6 min-max intervals in ioa_addr_in_range(), allowing an authenticated TURN client to relay to an IPv6 peer that is numerically within a configured non-prefix-aligned denied-peer-ip range but is classified as outside it. This issue is fixed in version 4.16.0.

Affected products

VendorProductAffectedFixed
coturn coturn < 4.16.0 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 coturn 4.18.0-1 —
Debian 13 coturn No fix yet —
Debian 12 coturn No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 coturn No fix yet —
Ubuntu 26.04 LTS coturn No fix yet —
Ubuntu 24.04 LTS coturn No fix yet —
Ubuntu 22.04 LTS coturn No fix yet —
Ubuntu 20.04 LTS coturn No fix yet —
Show 2 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 18.04 LTS coturn No fix yet —
Ubuntu 16.04 LTS coturn No fix yet —
ReleasePackageFixed inAdvisory
openSUSE Tumbleweed coturn 4.17.2-1.1 openSUSE-SU-2026:11617-1

Advisories 1

References