Vulnerability · Published Jun 25, 2026 · Assigned by wolfSSL
CVE-2026-6091Partial-chain verification accepts untrusted intermediate as trust anchor
Medium 6.0
In plain English
A medium-severity improper certificate validation in wolfSSL from wolfSSL. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Partial-chain certificate verification may accept chains that terminate at a peer-supplied, untrusted intermediate certificate rather than a trusted anchor. An attacker could present a chain that ends at an intermediate they control and have it accepted as valid. This affects the OpenSSL compatibility certificate-path-building path (wolfSSL_X509_verify_cert / X509_STORE, OPENSSL_EXTRA) when the X509_V_FLAG_PARTIAL_CHAIN verify flag is enabled.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | wolfssl | 5.9.2-r0 | ALPINE-CVE-2026-6091 |
| Debian:12 | wolfssl | no fix listed | DEBIAN-CVE-2026-6091 |
| Debian:13 | wolfssl | no fix listed | DEBIAN-CVE-2026-6091 |
| Ubuntu:22.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-6091 |
| Ubuntu:24.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-6091 |
| Ubuntu:25.10 | wolfssl | no fix listed | UBUNTU-CVE-2026-6091 |
| Ubuntu:26.04:LTS | wolfssl | no fix listed | UBUNTU-CVE-2026-6091 |
| Ubuntu:26.10 | wolfssl | no fix listed | UBUNTU-CVE-2026-6091 |
Affected products (as reported)
Weakness: CWE-295 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N