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CVE-2026-5066 zephyrproject-rtos CVE debrief

CVE-2026-5066 is a potential out-of-bounds write/read vulnerability in the TLS socket connect path of the network sockets subsystem. The vulnerability occurs when the TLS session cache is enabled, and the tls_session_store() and tls_session_restore() functions 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 and denial of service, and potentially to arbitrary code execution.

Vendor
zephyrproject-rtos
Product
Zephyr
CVSS
MEDIUM 6.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-04
Original CVE updated
2026-07-22
Advisory published
2026-06-04
Advisory updated
2026-07-22

Who should care

Developers and users of the Zephyr RTOS, as well as anyone using the affected network sockets subsystem.

Technical summary

The vulnerability is caused by a lack of validation of the addrlen value against the destination size in the tls_session_store() and tls_session_restore() functions. This allows an attacker to pass an addrlen larger than sizeof(struct net_sockaddr), causing the memcpy to read and write past the end of the address memory used by the TLS session cache.

Defensive priority

MEDIUM

Recommended defensive actions

  • Apply patches or updates provided by the vendor to fix the vulnerability.
  • Disable the TLS session cache if not required.
  • Validate user input to prevent passing an addrlen larger than sizeof(struct net_sockaddr).

Evidence notes

The vulnerability was reported by [email protected] and is tracked under GHSA-wgrc-jrf6-24f3.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-5066 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-5066

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-5066 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-5066

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.