Vulnerability in Wolfssl
CVE-2026-6091
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.
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (8.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 8th percentile — 8.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Wolfssl — versions 5.7.4
Weakness classification (CWE)
References
- github.com/wolfSSL/wolfssl/pull/10170 (Patch, patch, Issue Tracking)
- www.wolfssl.com/docs/security-vulnerabilities/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-6091?
- CVE-2026-6091 is a medium-severity vulnerability in Wolfssl, classified under Improper Certificate Validation. CVSS score: 6.5/10. Published 2026-06-25.
- How severe is CVE-2026-6091?
- Medium severity. CVSS v3 base score is 6.5 out of 10.