EUVD-2026-21216
GHSA-f5fh-xmxq-55p9
Severity by source
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/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:L/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:H/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
Lifecycle Timeline
3DescriptionCVE.org
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.
AnalysisAI
wolfSSL versions up to 5.9.0 allow arbitrary memory deallocation via unsafe deserialization of poisoned session cache data. An attacker with high privileges who can inject a crafted session into the cache and trigger specific session restore API calls can cause memory corruption with availability impact. No public exploit code or active exploitation has been confirmed; the vulnerability requires precise conditions including local access, high privileges, and user interaction.
Technical ContextAI
The vulnerability stems from unsafe deserialization of session objects stored in the session cache (CWE-502: Deserialization of Untrusted Data). When wolfSSL restores a session from cache, it deserializes a pointer embedded in the serialized session data and passes it directly to a free operation without validation or bounds checking. This is a classic use-after-free precursor where an attacker-controlled pointer value is treated as a valid memory address. The attack surface is restricted to scenarios where an attacker can directly manipulate the session cache storage mechanism and the application must invoke session restore APIs that process the poisoned data. The local attack vector (AV:L), high privilege requirement (PR:H), and user interaction dependency (UI:P) significantly constrain real-world exploitability despite the unsafe operation.
RemediationAI
Upgrade wolfSSL to version 5.10.0 or later. A fix is available via upstream pull request PR #10088 on the wolfSSL GitHub repository (https://github.com/wolfSSL/wolfssl/pull/10088), which addresses the unsafe deserialization by validating pointers before freeing session cache data. For systems unable to upgrade immediately, restrict session cache write access to trusted processes only, disable session caching if not essential, and ensure only authenticated, privileged users can trigger session restore operations. Consult the official wolfSSL security advisory at https://nvd.nist.gov/vuln/detail/CVE-2026-5507 for vendor-specific guidance.
wolfSSL prior to version 3.12.2 provides a weak Bleichenbacher oracle when any TLS cipher suite using RSA key exchange i
A specially crafted x509 certificate can cause a single out of bounds byte overwrite in wolfSSL through 3.10.2 resulting
wolfSSL (formerly CyaSSL) before 3.6.8 allows remote attackers to cause a denial of service (resource consumption or tra
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wolfSSL 4.3.0 has mulmod code in wc_ecc_mulmod_ex in ecc.c that does not properly resist timing side-channel attacks. Ra
In wolfSSL 4.1.0 through 4.2.0c, there are missing sanity checks of memory accesses in parsing ASN.1 certificate data wh
An issue was discovered in wolfSSL before 4.5.0, when single precision is not employed. Rated high severity (CVSS 7.0).
wolfSSL before 4.5.0 mishandles TLS 1.3 server data in the WAIT_CERT_CR state, within SanityCheckTls13MsgReceived() in t
wolfSSL (formerly CyaSSL) before 3.6.8 does not properly handle faults associated with the Chinese Remainder Theorem (CR
An issue was discovered in wolfSSL before 5.5.0 (when --enable-session-ticket is used); however, only version 5.3.0 is e
wolfSSL 4.6.x through 4.7.x before 4.8.0 does not produce a failure outcome when the serial number in an OCSP request di
Same weakness CWE-502 – Deserialization of Untrusted Data
View allSame technique Deserialization
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External POC / Exploit Code
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