CVE-2026-8718 zephyrproject CVE debrief

Who should care

Users of Zephyr with CONFIG_MBEDTLS_SSL_DTLS_CONNECTION_ID and CONFIG_USERSPACE enabled, as well as administrators of systems using DTLS sockets, should take immediate action to patch vulnerable systems and restrict optlen values to prevent buffer overflows. Unprivileged users with access to connected DTLS sockets can trigger a heap buffer overflow; prioritize patching and restrict optlen values. Monitor for suspicious activity on DTLS sockets and review compensating controls for exposed systems while remediation is scheduled and verified. Affected operator, platform, vulnerability-management, and security-team impact should be carefully evaluated to ensure proper mitigation and remediation efforts are in place. This includes reviewing the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance, and planning vendor-supported updates or mitigations through normal change control where exposure is confirmed. Additionally, checking relevant monitoring, detection, and logs for exposed assets that need extra review is crucial. Tracking exceptions, retesting remediated assets, and closing the item only after evidence is documented are also essential steps in the remediation process. Asset inventory management and rollback/change windows should be considered to minimize potential impact and ensure a smooth remediation process. Source tracking and monitoring can help in identifying potential security breaches and aid in the swift remediation of the vulnerability. Compensating controls, such as implementing additional security measures, can be put in place while patching is being implemented. It is essential to confirm whether affected product deployments exist in managed environments and assign an owner for follow-up to ensure that all necessary steps are taken to mitigate the vulnerability effectively. The vulnerability management team should work closely with the security team to ensure that all necessary steps are taken to mitigate the vulnerability effectively. The security team should review the vulnerability and implement necessary controls to prevent exploitation. The IT team should implement patches and monitor for any潜在

Technical summary

The tls_opt_dtls_peer_connection_id_value_get() function in subsys/net/lib/sockets/sockets_tls.c did not verify the buffer size before passing it to mbedtls_ssl_get_peer_cid(), causing potential buffer overflows. Unprivileged users can induce kernel-heap buffer overflows via small optlen values on connected DTLS sockets with Connection ID enabled. The vulnerability requires CONFIG_MBEDTLS_SSL_DTLS_CONNECTION_ID, an established DTLS session with a negotiated peer CID, and (for the kernel-crossing case) CONFIG_USERSPACE. The defect was introduced when the TLS_DTLS_CID option was added (v3.5.0).

Defensive priority

Unprivileged users with access to connected DTLS sockets can trigger a heap buffer overflow; prioritize patching and restrict optlen values.

Recommended defensive actions

• Patch vulnerable systems with vendor-supplied updates
• Restrict optlen values to prevent buffer overflows
• Monitor for suspicious activity on DTLS sockets
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The tls_opt_dtls_peer_connection_id_value_get() function passed caller-supplied optval directly to mbedtls_ssl_get_peer_cid() without verifying buffer size, causing potential buffer overflows. CONFIG_USERSPACE builds allow unprivileged users to induce kernel-heap buffer overflows via small optlen values on connected DTLS sockets with Connection ID enabled.

Sources and 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.