CVE-2026-80841
Low risk· EPSS 6%Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
In the Linux kernel, a vulnerability in the AF_PACKET subsystem related to TX_RING buffers has been fixed. The issue was that skb descriptors held a raw pointer to a ring frame, which could point to a no-longer-existing vmalloc mapping after pg_vec was freed. The fix defers the reference release until after timestamp and frame status writes, and adds an additional check before ring replacement.
Risk Assessment
The vulnerability may lead to a use-after-free in the kernel, potentially causing system crash, privilege escalation, or information leak. An attacker with local access and the ability to create AF_PACKET sockets could exploit this flaw.
Recommendation
It is recommended to immediately update the Linux kernel to a version containing the fix (commit for CVE-2026-80841). Monitor system distributions and apply appropriate security patches.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: net/packet: defer vmalloc TX_RING free until skbs finish AF_PACKET TX_RING skbs keep a raw pointer to their ring frame. The skb page references preserve page-backed ring blocks after pg_vec is freed, but they do not preserve a vmalloc mapping. tpacket_destruct_skb() currently drops the pending reference before writing the timestamp and TP_STATUS_AVAILABLE to the frame. Move the decrement after those stores. The smp_wmb() in __packet_set_status() orders the frame stores before the decrement. Also recheck pending TX frames under pg_vec_lock before non-closing ring replacement, so a racing send cannot add a pending skb between the initial check and the ring swap. Ring allocation can produce a mixture of page-backed and vmalloc-backed blocks. Allocate deferred-work storage during TX ring setup when the first vmalloc-backed block is encountered, and keep its pointer in the pg_vec allocation header. If allocation fails, return -ENOMEM from ring setup. On socket close, a non-NULL pointer identifies a vmalloc-backed vector without a scan. If TX skbs remain, defer the whole vector to system_long_wq. After pg_vec is detached, a late destructor can skip the pending decrement. Use socket write-memory accounting as the deferred lifetime gate instead: an skb remains charged through its final sock_wfree(), after all ring-frame accesses. The delayed work retains a socket reference and reschedules itself until no TX skbs remain. Move pending_refcnt release to packet_sock_destruct() so late skb destructors and deferred cleanup can safely use it after packet_release(). Page-backed teardown remains synchronous, and no lock is added to the TX completion hot path.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS