Vulnerability in Litespeedtech Openlitespeed
CVE-2026-119559
OpenLiteSpeed through 1.9.4 contains an authentication bypass vulnerability that allows unauthenticated remote attackers to evade virtual host client certificate requirements over HTTP/3. Because QuicStream inherits a verifyContext() implementation that always returns true, attackers can present a non-mTLS host's SNI with a protected Host header to access protected content.
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/litespeedtech/openlitespeed/blob/v1.9.4/src/http/httpsession.cpp (technical-description)
- github.com/litespeedtech/openlitespeed/blob/v1.9.4/src/sslpp/hiocrypto.h (technical-description)
- github.com/litespeedtech/openlitespeed/blob/v1.9.4/src/quic/quicstream.h (technical-description)
- abraxaslabs.tech/research/openlitespeed-h3-mtls-verifycontext (third-party-advisory)
- github.com/litespeedtech/openlitespeed (product)
- www.vulncheck.com/advisories/openlitespeed-through-1.9.4-mtls-bypass-via-http-3… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-119559?
- CVE-2026-119559 is a medium-severity vulnerability in Litespeedtech Openlitespeed, classified under Improper Certificate Validation. CVSS score: 5.9/10. Published 2026-10-30.
- How severe is CVE-2026-119559?
- Medium severity. CVSS v3 base score is 5.9 out of 10.