How severe is CVE-2026-5188?

CVE-2026-5188 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability high.

Is CVE-2026-5188 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-5188?

CVE-2026-5188 affects Wolfssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-5188?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-5188 have an EU (EUVD) identifier?

Yes. CVE-2026-5188 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21290.

When was CVE-2026-5188 published?

CVE-2026-5188 was published on 2026-04-10 and last updated on 2026-06-17.

CVE-2026-5188

CVE-2026-5188 is a high-severity vulnerability in Wolfssl with a CVSS 3.x base score of 8.1. 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-191.

Key facts

Severity: High (CVSS 3.x base score 8.1)
CVSS v4: 2.3
EPSS exploit prediction: 0% (3rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-21290
Weakness: CWE-191
Affected product: Wolfssl
Published: 2026-04-10
Last modified: 2026-06-17

Description

An integer underflow issue exists in wolfSSL when parsing the Subject Alternative Name (SAN) extension of X.509 certificates. A malformed certificate can specify an entry length larger than the enclosing sequence, causing the internal length counter to wrap during parsing. This results in incorrect handling of certificate data. The issue is limited to configurations using the original ASN.1 parsing implementation which is off by default.

Frequently asked questions

What is CVE-2026-5188?: An integer underflow issue exists in wolfSSL when parsing the Subject Alternative Name (SAN) extension of X.509 certificates. A malformed certificate can specify an entry length larger than the enclosing sequence, causing the internal length counter to wrap during parsing. This results in incorrect handling of certificate data. The issue is limited to configurations using the original ASN.1 parsing implementation which is off by default.
How severe is CVE-2026-5188?: CVE-2026-5188 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2026-5188 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-5188?: CVE-2026-5188 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-5188?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-5188 have an EU (EUVD) identifier?: Yes. CVE-2026-5188 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21290.
When was CVE-2026-5188 published?: CVE-2026-5188 was published on 2026-04-10 and last updated on 2026-06-17.

References

https://github.com/wolfSSL/wolfssl/pull/10024

Affected products (1)

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

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