Pre-authentication heap disclosure via signedness conversion
Published Jul 31, 2026 · Updated Jul 31, 2026
Out-of-bounds read in coturn 4.5.2 through 4.14.0 allows remote attackers to disclose process heap data through an HTTP request. try_acme_redirect stores a negative is_acme_req result in an unsigned size_t, bypasses rejection, and formats an unterminated receive-buffer path into the 301 Location header. Exploitation requires --acme-redirect and a reachable plaintext-TCP listener; responses can expose recycled data such as credentials, tokens, or relayed payloads.
Summary
What happened
Out-of-bounds read in coturn 4.5.2 through 4.14.0 allows remote attackers to disclose process heap data through an HTTP request. try_acme_redirect stores a negative is_acme_req result in an unsigned size_t, bypasses rejection, and formats an unterminated receive-buffer path into the 301 Location header. Exploitation requires --acme-redirect and a reachable plaintext-TCP listener; responses can expose recycled data such as credentials, tokens, or relayed payloads.
The record
- CVE
- CVE-2026-62959
- Published
- Jul 31, 2026
- Updated
- Jul 31, 2026
- Vendor
- coturn
- Product
- coturn
- Classifications
- CWE-195, CWE-125, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 31, 2026CVE publishedPublication date reported by the CVE source.
- Jul 31, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 4.5.2, < 4.15.0
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.
Weakness, pattern, technique
Public exploit references
- acme-preauth-heap-mem-disc proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo