Is CVE-2026-6091 in the CISA KEV catalog?

No. CVE-2026-6091 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-6091?

CVE-2026-6091 has a CVSS v3 base score of 6.5 (Moderate).

What is the EPSS score for CVE-2026-6091?

CVE-2026-6091 has an EPSS score of 0.12% (2th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-6091?

Upgrade wolfssl to 5.9.2 or later.

CVE & CISA-KEV Catalog

CVE-2026-6091

MEDIUM

6.5

CVSS v3

NVD

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.

CWE-295Improper Certificate Validation

How to fix

Remediation Available

wolfsslNVD

Affected:>= 5.7.4, < 5.9.2Fixed in:5.9.2CVE-2026-6091derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Exploit Intelligence

0.12%probability of exploitation in 30 days

2ndpercentile

Low risk: more likely to be exploited than 2% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

wolfssl.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-26.