How severe is CVE-2026-6091?

CVE-2026-6091 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-6091 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-6091?

CVE-2026-6091 affects Wolfssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-6091?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-6091 have an EU (EUVD) identifier?

Yes. CVE-2026-6091 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39486.

When was CVE-2026-6091 published?

CVE-2026-6091 was published on 2026-06-25 and last updated on 2026-06-26.

CVE-2026-6091

CVE-2026-6091 is a medium-severity vulnerability in Wolfssl with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-295.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 6.0
EPSS exploit prediction: 0% (2nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-39486
Weakness: CWE-295
Affected product: Wolfssl
Published: 2026-06-25
Last modified: 2026-06-26

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-6091?: CVE-2026-6091 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-6091 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-6091?: CVE-2026-6091 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-6091?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-6091 have an EU (EUVD) identifier?: Yes. CVE-2026-6091 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39486.
When was CVE-2026-6091 published?: CVE-2026-6091 was published on 2026-06-25 and last updated on 2026-06-26.

References

Affected products (1)

cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*

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