CVE-2026-52972 Linux Kernel af_alg AEAD Integer Overflow DoS Vulnerability

Technical summary

CVE-2026-52972 is an integer overflow vulnerability in the Linux kernel's af_alg (Application Family socket for cryptographic algorithms) subsystem. The vulnerability exists in the AEAD associated data (AD) length validation logic. Without a cap on the AD length parameter, arithmetic operations performed during TX buffer size validation can overflow, leading to memory allocation failures or denial of service. The fix implements a cap of 0x80000000 (2GB) on the AEAD AD length to prevent overflow conditions during buffer calculations.

Business impact

This vulnerability can disrupt cryptographic services and applications relying on kernel-level AEAD operations through denial of service. Organizations using Linux systems for security-sensitive workloads—including VPN gateways, encrypted storage systems, or TLS acceleration—may experience service interruptions if this flaw is exploited. The impact is primarily availability-focused rather than confidentiality or integrity, but application crashes can cascade to dependent services.

Affected systems

The vulnerability affects Linux kernel implementations that include the af_alg subsystem with AEAD cipher support. Any distribution or embedded system running a vulnerable kernel version is at risk. Organizations should consult their distribution's security advisories to determine which specific kernel versions are affected and the corresponding patch schedules.

Exploitability

Exploitation requires local system access and standard (non-root) user privileges, making this vulnerability less attractive to remote attackers but viable for local privilege escalation or lateral movement scenarios. No known public exploits have been documented in the kernel vulnerabilities database, and this is not tracked as an in-the-wild exploitation target. The barrier to exploitation is moderate—an attacker must craft specific AEAD requests, but no specialized tools or complex conditions are required.

Remediation

Apply kernel security updates that include the fix capping AEAD AD length to 0x80000000. Most mainstream distributions have already released or are preparing patches. Verify the specific patched kernel version from your distribution's security advisory, as version numbers vary. For systems unable to patch immediately, consider restricting local user access and reviewing application-level access controls for cryptographic services.

Patch guidance

Monitor your Linux distribution's security bulletins for kernel updates addressing this vulnerability. Patch versions vary by distribution (Red Hat, Debian, Ubuntu, SUSE, etc.); refer to your vendor's advisory for exact version numbers and deployment timelines. Coordinate kernel patching with change management protocols, as it typically requires a system reboot. Test patches in non-production environments before production deployment.

Detection guidance

Look for failed AEAD cipher operations, kernel crashes, or out-of-memory errors in systems processing large cryptographic operations. Monitor kernel logs for af_alg-related errors or buffer allocation failures. Network-based detection is limited due to the local nature of the vulnerability; focus on endpoint monitoring for suspicious cryptographic API calls with abnormally large parameters from non-privileged processes.

Why prioritize this

While the CVSS score of 5.5 (MEDIUM) reflects the local-access requirement and availability-only impact, this vulnerability should be prioritized for patching to maintain the integrity of cryptographic services. Organizations with strict availability requirements, especially those running cryptographic appliances or middleware, should treat this as moderately urgent. The lack of in-the-wild exploitation provides a reasonable window for controlled, planned patching.

Risk score, explained

The CVSS 3.1 vector (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) reflects a local attack vector (AV:L) with low attack complexity (AC:L), requiring low privileges (PR:L) and no user interaction (UI:N). The high availability impact (A:H) combined with no impact to confidentiality or integrity yields a MEDIUM severity rating of 5.5. The underlying integer overflow flaw (CWE-190) is correctly scoped to the affected system only (S:U) with no cross-boundary spillover.

Frequently asked questions