High 7.2Published Feb 24, 2026

CVE-2026-27624Coturn: IPv4-mapped IPv6 (::ffff:0:0/96) bypasses denied-peer-ip ACL

Updated under an hour ago (Oct 27, 2026, 9:23 AM ET)

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Every CVE for coturn

Exploited in the last 30 days

Coturn is a free open source implementation of TURN and STUN Server. Coturn is commonly configured to block loopback and internal ranges using "denied-peer-ip" and/or default loopback restrictions. CVE-2020-26262 addressed bypasses involving "0.0.0.0", "[::1]" and "[::]", but IPv4-mapped IPv6 is not covered. When sending a "CreatePermission" or "ChannelBind" request with the "XOR-PEER-ADDRESS" value of "::ffff:127.0.0.1", a successful response is received, even though "127.0.0.0/8" is blocked via "denied-peer-ip". The root cause is that, prior to the updated fix implemented in version 4.9.0, three functions in "src/client/ns_turn_ioaddr.c" do not check "IN6_IS_ADDR_V4MAPPED". "ioa_addr_is_loopback()" checks "127.x.x.x" (AF_INET) and "::1" (AF_INET6), but not "::ffff:127.0.0.1." "ioa_addr_is_zero()" checks "0.0.0.0" and "::", but not "::ffff:0.0.0.0." "addr_less_eq()" used by "ioa_addr_in_range()" for "denied-peer-ip" matching: when the range is AF_INET and the peer is AF_INET6, the comparison returns 0 without extracting the embedded IPv4. Version 4.9.0 contains an updated fix to address the bypass of the fix for CVE-2020-26262.

CVSS: 7.2 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Weakness (CWE): CWE-284, CWE-441
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Feb 25, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

coturn coturn coturn:coturn (from the name)	before 4.9.0	CNA record
coturn_project coturn coturn_project:coturn	before 4.9.0	NVD

References

References

https://github.com/coturn/coturn/security/advisories/GHSA-j8mm-mpf8-gvjg	x-refsource-confirm, exploit, vendor-advisory
https://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7p	x-refsource-misc, not-applicable
https://github.com/coturn/coturn/commit/b80eb898ba26552600770162c26a8ae7f3661b0b	x-refsource-misc, patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.