What’s Vulnerable › Vulnerabilities

CVE-2026-2646: Heap buffer overflow in session parsing with wolfSSL_d2i_SSL_SESSION() function

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-19 · updated 2026-06-17
• Weakness: CWE-122

Description

A heap-buffer-overflow vulnerability exists in wolfSSL's wolfSSL_d2i_SSL_SESSION() function. When deserializing session data with SESSION_CERTS enabled, certificate and session id lengths are read from an untrusted input without bounds validation, allowing an attacker to overflow fixed-size buffers and corrupt heap memory. A maliciously crafted session would need to be loaded from an external source to trigger this vulnerability. Internal sessions were not vulnerable.

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/9748
• https://github.com/wolfSSL/wolfssl/pull/9949

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