Linux Kernel io_uring/Poll multishot recv hang due to missing EOF
CVE-2026-23473 Published on April 3, 2026
io_uring/poll: fix multishot recv missing EOF on wakeup race
In the Linux kernel, the following vulnerability has been resolved:
io_uring/poll: fix multishot recv missing EOF on wakeup race
When a socket send and shutdown() happen back-to-back, both fire
wake-ups before the receiver's task_work has a chance to run. The first
wake gets poll ownership (poll_refs=1), and the second bumps it to 2.
When io_poll_check_events() runs, it calls io_poll_issue() which does a
recv that reads the data and returns IOU_RETRY. The loop then drains all
accumulated refs (atomic_sub_return(2) -> 0) and exits, even though only
the first event was consumed. Since the shutdown is a persistent state
change, no further wakeups will happen, and the multishot recv can hang
forever.
Check specifically for HUP in the poll loop, and ensure that another
loop is done to check for status if more than a single poll activation
is pending. This ensures we don't lose the shutdown event.
Products Associated with CVE-2026-23473
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Affected Versions
Linux:- Version dbc2564cfe0faff439dc46adb8c009589054ea46 and below 0f4ce79b8db7b040373fc664c8bc6c5fd74bd196 is affected.
- Version dbc2564cfe0faff439dc46adb8c009589054ea46 and below bf33554b6abf7e7faeadd8af1b82037ea755a6bb is affected.
- Version dbc2564cfe0faff439dc46adb8c009589054ea46 and below a68ed2df72131447d131531a08fe4dfcf4fa4653 is affected.
- Version 5.19 is affected.
- Before 5.19 is unaffected.
- Version 6.18.20, <= 6.18.* is unaffected.
- Version 6.19.10, <= 6.19.* is unaffected.
- Version 7.0-rc5, <= * is unaffected.