CVE-2026-46015
Analyzed Analyzed - Analysis Complete
Linux Kernel TCP Socket Migration Race Condition

Publication date: 2026-05-27

Last updated on: 2026-06-16

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: tcp: call sk_data_ready() after listener migration When inet_csk_listen_stop() migrates an established child socket from a closing listener to another socket in the same SO_REUSEPORT group, the target listener gets a new accept-queue entry via inet_csk_reqsk_queue_add(), but that path never notifies the target listener's waiters. A nonblocking accept() still works because it checks the queue directly, but poll()/epoll_wait() waiters and blocking accept() callers can also remain asleep indefinitely. Call READ_ONCE(nsk->sk_data_ready)(nsk) after a successful migration in inet_csk_listen_stop(). However, after inet_csk_reqsk_queue_add() succeeds, the ref acquired in reuseport_migrate_sock() is effectively transferred to nreq->rsk_listener. Another CPU can then dequeue nreq via accept() or listener shutdown, hit reqsk_put(), and drop that listener ref. Since listeners are SOCK_RCU_FREE, wrap the post-queue_add() dereferences of nsk in rcu_read_lock()/rcu_read_unlock(), which also covers the existing sock_net(nsk) access in that path. The reqsk_timer_handler() path does not need the same changes for two reasons: half-open requests become readable only after the final ACK, where tcp_child_process() already wakes the listener; and once nreq is visible via inet_ehash_insert(), the success path no longer touches nsk directly.
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Meta Information
Published
2026-05-27
Last Modified
2026-06-16
Generated
2026-06-16
AI Q&A
2026-05-27
EPSS Evaluated
2026-06-15
NVD
CVE-2026-46015
EUVD
EUVD-2026-32396
Affected Vendors & Products
Showing 6 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 6.7 (inc) to 6.12.86 (exc)
linux linux_kernel From 5.16 (inc) to 6.1.175 (exc)
linux linux_kernel From 6.2 (inc) to 6.6.140 (exc)
linux linux_kernel From 5.14 (inc) to 5.15.209 (exc)
linux linux_kernel From 6.13 (inc) to 6.18.27 (exc)
linux linux_kernel From 6.19 (inc) to 7.0.4 (exc)
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability exists in the Linux kernel's TCP implementation related to socket listener migration within the SO_REUSEPORT group. When an established child socket is migrated from a closing listener to another listener socket, the new listener receives a new accept-queue entry but does not notify waiting processes properly. As a result, blocking accept() calls and poll()/epoll_wait() waiters can remain asleep indefinitely, causing them to hang.

The fix involves calling sk_data_ready() after a successful migration to notify waiters. Additionally, the code was adjusted to safely handle references to listener sockets using RCU (Read-Copy-Update) locking to prevent premature freeing of listener references during concurrent operations.

Impact Analysis

This vulnerability can cause processes that are waiting on a socket listener to accept new connections to hang indefinitely. Specifically, blocking accept() calls and poll()/epoll_wait() waiters may never be notified of incoming connections, leading to potential denial of service conditions where applications become unresponsive or fail to accept new network connections.

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