CVE-2023-34324: Possible deadlock in Linux kernel event handling

Severity: medium (CVSS 4.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-01-05 · updated 2026-06-17
Weakness: CWE-400

Description

Closing of an event channel in the Linux kernel can result in a deadlock. This happens when the close is being performed in parallel to an unrelated Xen console action and the handling of a Xen console interrupt in an unprivileged guest. The closing of an event channel is e.g. triggered by removal of a paravirtual device on the other side. As this action will cause console messages to be issued on the other side quite often, the chance of triggering the deadlock is not neglectable. Note that 32-bit Arm-guests are not affected, as the 32-bit Linux kernel on Arm doesn't use queued-RW-locks, which are required to trigger the issue (on Arm32 a waiting writer doesn't block further readers to get the lock).

Affected products

Linux kernel: before 5.10 — fixed in 5.10
xen: all versions

How to fix

Upgrade to a fixed version: Linux kernel 5.10. Check the vendor advisory for mitigations.

References

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