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

Quick assessment

Affected
OpenBSD LibreSSL
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

LibreSSL 的 ocspcheck 组件（版本 4.4.0 及更早版本）存在明文传输漏洞：由于 url2host() 函数会丢弃 OCSP URL 的协议方案（scheme），而 http_alloc() 函数仅对 443 端口启用 TLS，导致攻击者若处于通信路径上，便可窃听发送至非 443 端口的 HTTPS 响应器 URL 的 OCSP 请求。这将暴露证书序列号、颁发者哈希值以及随机数（nonce）等敏感信息。

CVSS 3.7 · Low

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-118373

Vulnerability Information
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Vulnerability Title
LibreSSL ocspcheck through 4.4.0 Cleartext Transmission of OCSP Requests via url2host()
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
敏感数据的明文传输
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
OpenBSD LibreSSL 0 ~ 4.4.0 -

II. Public POCs for CVE-2026-118373

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III. Intelligence Information for CVE-2026-118373

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Patches & Fixes for CVE-2026-118373 (2)

Vendor Pages for CVE-2026-118373 (3)

Same Patch Batch · OpenBSD · 2026-10-28 · 4 CVEs total

CVE-2026-118374 5.9 MEDIUM LibreSSL ocspcheck through 4.4.0 Memory Exhaustion via Unbounded OCSP HTTP Response
CVE-2026-118371 3.7 LOW LibreSSL through 4.4.0 CRLF Injection via OCSP_sendreq_new() Request Line
CVE-2026-118372 3.7 LOW LibreSSL ocspcheck through 4.4.0 CRLF Injection via AIA OCSP URL Path

IV. Related Vulnerabilities

Same product: LibreSSL
Same vendor: OpenBSD
Same weakness: CWE-319