What’s Vulnerable › Vulnerabilities

CVE-2026-118373: LibreSSL ocspcheck through 4.4.0 Cleartext Transmission of OCSP Requests via url2host()

• Severity: low (CVSS 3.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-28 · updated 2026-10-28
• Weakness: CWE-319

Description

LibreSSL ocspcheck through 4.4.0 contains a cleartext transmission vulnerability because url2host() discards the OCSP URL scheme and http_alloc() only selects TLS for port 443. On-path network attackers can read OCSP requests sent to https responder URLs on non-443 ports, exposing certificate serial numbers, issuer hashes, and nonces.

Affected products

• OpenBSD Libressl: through 4.4.0

References

• https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-4.4.0-relnotes.txt
• https://github.com/libressl/portable
• https://github.com/openbsd/src/blob/17a8e44328ee2505d69723a126a390a526e50370/usr.sbin/ocspcheck/http.c#L299
• https://github.com/openbsd/src/commit/0f7039667044d1cd252cc72134e499186da4da25
• https://www.vulncheck.com/advisories/libressl-ocspcheck-through-4.4.0-cleartext-transmission-of-ocsp-requests-via-url2host

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