CVE-2026-93203 Linux CVE debrief

Who should care

Linux kernel developers and maintainers, system administrators responsible for Linux kernel updates, security teams monitoring Linux kernel vulnerabilities, and operators of systems using the affected Linux kernel versions. They should review kernel patch notes and referenced commits for affected versions and updates, assess exposure based on system configurations and Linux kernel versions in use, verify CRC validation and claim handling in local backbone

Why it matters

A vulnerability in the Linux kernel's batman-adv module could allow an attacker to corrupt CRC values, potentially leading to issues with claim validation and backbone updates. Defenders should review kernel patch notes and referenced commits for affected versions and updates, assess exposure based on system configurations and Linux kernel versions in use, verify CRC validation and claim handling in local backbone claims, and monitor for potential issues with claim validation and backbone updates.

• Verification of CRC validation and claim handling in local backbone claims
• Assessment of exposure based on system configurations and Linux kernel versions in use
• Monitoring for potential issues with claim validation and backbone updates
• Review of kernel patch notes and referenced commits for affected versions and updates

Technical summary

The batman-adv module in the Linux kernel has a vulnerability that could lead to CRC corruption due to parallel claim additions. This issue arises from the handling of claims and modifications to the backbone of claims for CLAIM frames from remote backbones and local packets. The vulnerability could lead to incorrect CRC values being used, affecting the validation of claims and updates to the backbone. The issue is resolved by splitting the functionality into clear separate parts: new claim and update of existing claim.

Defensive priority

Medium

Recommended defensive actions

• Review kernel patch notes and referenced commits for affected versions and updates
• Assess exposure based on system configurations and Linux kernel versions in use
• Verify CRC validation and claim handling in local backbone claims
• Monitor for potential issues with claim validation and backbone updates
• Perform a thorough review of system configurations and Linux kernel versions
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, but do not specify versions, exploitation, impact, or remediation. Official kernel references are provided. The vulnerability is caused by a race condition in the batadv_bla_add_claim() function, which can lead to CRC corruption. The issue is resolved by splitting the functionality into clear separate parts: new claim and update of existing claim.

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.