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Vulnerability · Published Apr 9, 2026 · Assigned by wolfSSL

CVE-2026-5507Session Cache Restore — Arbitrary Free via Deserialized Pointer

Medium 4.1

In plain English

A medium-severity unsafe deserialization in wolfSSL from wolfSSL. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)4.1Medium
Exploit odds (30 days)0.2%top 92.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

When restoring a session from cache, a pointer from the serialized session data is used in a free operation without validation. An attacker who can poison the session cache could trigger an arbitrary free. Exploitation requires the ability to inject a crafted session into the cache and for the application to call specific session restore APIs.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.23wolfssl5.9.1-r0ALPINE-CVE-2026-5507
Alpine:v3.24wolfssl5.9.1-r0ALPINE-CVE-2026-5507
Debian:12wolfsslno fix listedDEBIAN-CVE-2026-5507
Debian:13wolfsslno fix listedDEBIAN-CVE-2026-5507
Ubuntu:22.04:LTSwolfsslno fix listedUBUNTU-CVE-2026-5507
Ubuntu:24.04:LTSwolfsslno fix listedUBUNTU-CVE-2026-5507
Ubuntu:25.10wolfsslno fix listedUBUNTU-CVE-2026-5507
Ubuntu:26.04:LTSwolfsslno fix listedUBUNTU-CVE-2026-5507
Ubuntu:26.10wolfsslno fix listedUBUNTU-CVE-2026-5507

Affected products (as reported)

VendorProductVersions
wolfSSL wolfSSL 0 – through 5.9.0

Weakness: CWE-502 · Vector: CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References