Description
LibreSSL ocspcheck through 4.4.0 contains a CRLF injection vulnerability that allows attackers to inject HTTP headers by embedding CR/LF sequences in a certificate's AIA OCSP URI path. Because url2host() copies the path without rejecting control characters and http_open() places it in the POST request line, attackers can inject headers or split OCSP requests sent to the responder host.
References7
- ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-4.4.0-relnotes.txt
- github.com/libressl/portable
- github.com/openbsd/src/blob/17a8e44328ee2505d69723a126a390a526e…
- github.com/openbsd/src/blob/17a8e44328ee2505d69723a126a390a526e…
- github.com/openbsd/src/commit/3adb7688a5bcfb675fa6d8b10e242022d…
- github.com/openbsd/src/commit/6efdc4cce3fac9fa7208a9452f84de34c…
- www.vulncheck.com/advisories/libressl-ocspcheck-through-4.4.0-c…
Metrics
- CVSS 3.1
-
3.7
LOW
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N - CVSS 4.0
-
6.3
MEDIUM
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 4 · as of 2 November 2026
- CWE
- CWE-93
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.