CVE-2026-5066
MediumCVSS 6.3Exploitation Probability (EPSS)
Low risk12th percentile - higher than 12% of all known CVEs
Summary
A potential out-of-bounds write/read exists in the TLS socket connect path of the network sockets subsystem (subsys/net/lib/sockets/sockets_tls.c). When the TLS session cache is enabled, tls_session_store() and tls_session_restore() memcpy the caller-supplied address into a fixed-size buffer using the caller-controlled addrlen value without validating it against the destination size. This can lead to a crash, denial of service, and potentially to arbitrary code execution.
Risk Assessment
An attacker can exploit this vulnerability to cause a system crash (denial of service) or potentially execute arbitrary code, compromising the confidentiality, integrity, and availability of the system.
Recommendation
Immediately update Zephyr RTOS to a version containing the fix for CVE-2026-5066. If an update is not possible, temporarily disable the TLS session cache.
Original NVD description (English source)
A potential out-of-bounds write/read exists in the TLS socket connect path of the network sockets subsystem (subsys/net/lib/sockets/sockets_tls.c). When the TLS session cache is enabled, tls_session_store() and tls_session_restore() memcpy the caller-supplied address into a fixed-size buffer using the caller-controlled addrlen value without validating it against the destination size. struct net_sockaddr is an opaque type, so an application can pass an addrlen larger than sizeof(struct net_sockaddr) (for example 128 bytes into a 24-byte stack buffer), causing the memcpy to read and write past the end of the address memory used by the TLS session cache. This out-of-bounds write can lead to a crash and denial of service, and potentially to arbitrary code execution.