Buffer overflow in Zephyrproject Zephyr
CVE-2026-5066
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.003 (25.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.003 · change: -0.001
Affected products
Weakness classification (CWE)
References
- github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-wgrc-jrf6-24f3 (Exploit, Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-5066?
- CVE-2026-5066 is a medium-severity vulnerability in Zephyrproject Zephyr, classified under Out-of-bounds Write. CVSS score: 6.3/10. Published 2026-06-04.
- How severe is CVE-2026-5066?
- Medium severity. CVSS v3 base score is 6.3 out of 10.