Authenticated SSRF via IPv4-mapped loopback address
Published Jul 10, 2026 · Updated Jul 10, 2026
SSRF in coturn before 4.13.0 allows remote authenticated users to reach localhost services through crafted TURN peer addresses. ioa_addr_is_loopback tests the literal IPv6 loopback shape before IPv4-mapped IPv6 handling, misclassifying ::ffff:127.0.0.1 and bypassing good_peer_addr. Exploitation requires valid TURN credentials; an explicit denied-peer range for 127.0.0.0/8 blocks the bypass, while the default guard permits relay access to host-local services.
Summary
What happened
SSRF in coturn before 4.13.0 allows remote authenticated users to reach localhost services through crafted TURN peer addresses. ioa_addr_is_loopback tests the literal IPv6 loopback shape before IPv4-mapped IPv6 handling, misclassifying ::ffff:127.0.0.1 and bypassing good_peer_addr. Exploitation requires valid TURN credentials; an explicit denied-peer range for 127.0.0.0/8 blocks the bypass, while the default guard permits relay access to host-local services.
The record
- CVE
- CVE-2026-53450
- Published
- Jul 10, 2026
- Updated
- Jul 10, 2026
- Vendor
- coturn
- Product
- coturn
- Classifications
- CWE-918, T1090
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 10, 2026CVE publishedPublication date reported by the CVE source.
- Jul 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 4.13.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- coturn mapped-loopback proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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