Wolfssl CVE-2026-5188

Q: What is the CVSS score of CVE-2026-5188?

CVE-2026-5188 has a CVSS 4.0 base score of 2.3 (Low). CVSS vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.0%.

EUVD-2026-21290 LOW

Integer Underflow (CWE-191)

2026-04-10 wolfSSL

GHSA-9qgc-pcpx-g38q

Information Disclosure Integer Overflow Wolfssl

2.3

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

2.3 LOW

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

Scope

Lifecycle Timeline

EUVD ID Assigned

Apr 10, 2026 - 03:45 euvd

EUVD-2026-21290

Analysis Generated

Apr 10, 2026 - 03:45 vuln.today

CVE Published

Apr 10, 2026 - 03:24 nvd

LOW 2.3

DescriptionCVE.org

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.

AnalysisAI

Integer underflow in wolfSSL's ASN.1 certificate parser allows remote attackers to trigger information disclosure and potential memory access violations when processing malformed X.509 certificates with oversized Subject Alternative Name extensions. The vulnerability affects wolfSSL versions up to 5.9.0 but only impacts systems using the non-default original ASN.1 parsing implementation; no public exploit code or active exploitation has been identified at time of analysis.

Technical ContextAI

The vulnerability exists in wolfSSL's ASN.1 parsing implementation used to process X.509 certificate extensions, specifically the Subject Alternative Name (SAN) field. When parsing ASN.1 DER-encoded data, the parser maintains an internal length counter to track remaining bytes in a sequence. A malformed certificate can specify an entry length that exceeds the enclosing sequence's declared length, causing this counter to underflow (wrap around due to unsigned integer arithmetic, CWE-191). This integer underflow leads to incorrect buffer boundary calculations during subsequent parsing operations, potentially allowing out-of-bounds memory reads. The flaw is confined to systems explicitly using the original ASN.1 parser rather than the default implementation, significantly limiting real-world exposure.

RemediationAI

Upgrade to wolfSSL version 5.10.0 or later, which includes the fix for the ASN.1 integer underflow. If immediate patching is not feasible, disable or avoid explicit use of the original ASN.1 parsing implementation (the default configuration is safe). No workaround is available for systems requiring the legacy parser. Refer to the wolfSSL GitHub repository (https://github.com/wolfSSL/wolfssl/pull/10024) for technical details and verification that the fix has been applied in your deployed version.