CVE-2026-74666: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: packet: synchronize pressure clearing with ring reconfiguration packet_set_ring() updates the RX ring state under sk_receive_queue.lock, but used to publish the tpacket receive mode through po->prot_hook.func after releasing that lock. packet_poll() and packet_recvmsg() can then run the pressure clearing path after the ring has been cleared while still seeing tpacket_rcv, causing __packet_rcv_has_room() to dereference stale or NULL ring storage. Move the existing receive hook assignment into the same sk_receive_queue.lock section as the ring state update. Keep the assignment otherwise unchanged, including on TX ring reconfiguration, to avoid adding behavior changes that are not required for the fix. Serialize packet_recvmsg() pressure clearing with the same queue lock only after PACKET_SOCK_PRESSURE has been observed. If the flag is clear and the socket has moved away from tpacket_rcv, packet_set_ring() has already detached the socket and waited for synchronize_net(), so no new packet input can set the flag again. packet_poll() already holds sk_receive_queue.lock, so it uses the new unlocked helper directly.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 2ccdbaa6d55b0656244ba57c4b56765a0af76c0a, < cf8189b82bb93f219ab740e0346c919ad65ada62; >= 2ccdbaa6d55b0656244ba57c4b56765a0af76c0a, < ad740b4990347521f0db260d381f9f74e7b340ba; >= 2ccdbaa6d55b0656244ba57c4b56765a0af76c0a, < 2c7b5eb87b2b288cdbde825f21d2b83b2f5da747; >= 2ccdbaa6d55b0656244ba57c4b56765a0af76c0a, < a08196c3cc105947746ec21309edfbb60275fcdb; >= 2ccdbaa6d55b0656244ba57c4b56765a0af76c0a, < 1a35da325cac4d5bcad76a2aa943408a6f1d9000
Linux	Linux	4.2

References

Timeline

Published: Aug 22, 2026
Last Modified: Aug 22, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-74666?

In the Linux kernel, the following vulnerability has been resolved: packet: synchronize pressure clearing with ring reconfiguration packet_set_ring() updates the RX ring state under sk_receive_queue.lock, but used to publish the tpacket receive mode through po->prot_hook.func after releasing that lock. packet_poll() and packet_recvmsg() can then run the pressure clearing path after the ring has been cleared while still seeing tpacket_rcv, causing __packet_rcv_has_room() to dereference stale or NULL ring storage. Move the existing receive hook assignment into the same sk_receive_queue.lock section as the ring state update. Keep the assignment otherwise unchanged, including on TX ring reconfiguration, to avoid adding behavior changes that are not required for the fix. Serialize packet_recvmsg() pressure clearing with the same queue lock only after PACKET_SOCK_PRESSURE has been observed. If the flag is clear and the socket has moved away from tpacket_rcv, packet_set_ring() has already detached the socket and waited for synchronize_net(), so no new packet input can set the flag again. packet_poll() already holds sk_receive_queue.lock, so it uses the new unlocked helper directly.

How severe is CVE-2026-74666?

Severity scoring for CVE-2026-74666 is pending analysis.

How do I fix CVE-2026-74666?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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