CVE-2026-53124: ublk: reset per-IO canceled flag on each fetch

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-24 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: ublk: reset per-IO canceled flag on each fetch If a ublk server starts recovering devices but dies before issuing fetch commands for all IOs, cancellation of the fetch commands that were successfully issued may never complete. This is because the per-IO canceled flag can remain set even after the fetch for that IO has been submitted - the per-IO canceled flags for all IOs in a queue are reset together only once all IOs for that queue have been fetched. So if a nonempty proper subset of the IOs for a queue are fetched when the ublk server dies, the IOs in that subset will never successfully be canceled, as their canceled flags remain set, and this prevents ublk_cancel_cmd from actually calling io_uring_cmd_done on the commands, despite the fact that they are outstanding. Fix this by resetting the per-IO cancel flags immediately when each IO is fetched instead of waiting for all IOs for the queue (which may never happen).

Affected products

Linux kernel: from 6.14.6 before 6.15; from 6.15.1 before 7.0.10; 6.15, 6.15-rc3, 6.15-rc4, 6.15-rc5, 6.15-rc6, 6.15-rc7 — fixed in 6.15, 7.0.10

How to fix

Upgrade to a fixed version: Linux kernel 6.15, 7.0.10. Check the vendor advisory for mitigations.

References

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