CVE-2026-5066: zephyrproject-rtos zephyr Out-of-bounds Write

Vulnerability summary

CVE-2026-5066 is a high (CVSS 8.8) Out-of-bounds Write vulnerability in zephyrproject-rtos zephyr. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 39.3% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 04-06-2026
   PublishedVulnerability first disclosed.
2. 15-10-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.