# CVE-2026-118374: LibreSSL ocspcheck through 4.4.0 Memory Exhaustion via Unbounded OCSP HTTP Response

Status: published. Published: 2026-10-28. Updated: 2026-11-02.

LibreSSL ocspcheck through 4.4.0 contains a memory exhaustion vulnerability that allows malicious OCSP responders to exhaust memory by sending unbounded HTTP responses. Attackers controlling the responder or intercepting plain HTTP AIA OCSP traffic can stream endless headers or body data to http_head_read() and http_body_read(), denying certificate status checks.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/openbsd/src/commit/bf5da63f53179ef423d18c56d6da89eaefb56228
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/openbsd/src/commit/de4274c56c9ace88232591d4c919d79281a8de59

## Affected products and versions

- OpenBSD / LibreSSL (libressl/portable): ≥ 0; ≤ 4.4.0 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 8.2 (high); CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 5.9 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: 0.21% as of 2026-11-02; percentile 11.44%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-770

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/openbsd/src/commit/bf5da63f53179ef423d18c56d6da89eaefb56228 (CNA: VulnCheck; patch)

- https://github.com/openbsd/src/commit/de4274c56c9ace88232591d4c919d79281a8de59 (CNA: VulnCheck; patch)

- https://github.com/openbsd/src/blob/f6f428241d469cf434e60b73fc834d0448f068d5/usr.sbin/ocspcheck/http.c#L419 (CNA: VulnCheck; technical-description)

- https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-4.4.0-relnotes.txt (CNA: VulnCheck; release-notes)

- https://github.com/libressl/portable (CNA: VulnCheck; product)

- https://www.vulncheck.com/advisories/libressl-ocspcheck-through-4.4.0-memory-exhaustion-via-unbounded-ocsp-http-response (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-118374; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-118374; retrieved 2026-11-02; source updated Not reported

Revision: aaa3ba847deef3d8566e88b6486c1b3b0fb781da8e648344bceb9eaab05dace1

Canonical: https://y2.dev/cve/CVE-2026-118374

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