What’s Vulnerable › Vulnerabilities

CVE-2026-3548: Buffer overflow in CRL number parsing in wolfSSL

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-19 · updated 2026-06-17
• Weakness: CWE-122

Description

Two buffer overflow vulnerabilities existed in the wolfSSL CRL parser when parsing CRL numbers: a heap-based buffer overflow could occur when improperly storing the CRL number as a hexadecimal string, and a stack-based overflow for sufficiently sized CRL numbers. With appropriately crafted CRLs, either of these out of bound writes could be triggered. Note this only affects builds that specifically enable CRL support, and the user would need to load a CRL from an untrusted source.

Affected products

• wolfSSL: before 5.9.0 — fixed in 5.9.0

How to fix

Upgrade to a fixed version: wolfSSL 5.9.0. Check the vendor advisory for mitigations.

References

• https://github.com/wolfSSL/wolfssl/pull/9628/
• https://github.com/wolfSSL/wolfssl/pull/9873/

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