Time-of-check Time-of-use (TOCTOU) Affecting kernel-rt-doc package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-CENTOS7-KERNELRTDOC-18686187
- published12 Aug 2026
- disclosed10 Aug 2026
Introduced: 10 Aug 2026
NewCVE-2026-68329 (opens in a new tab)How to fix?
There is no fixed version for Centos:7 kernel-rt-doc.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-rt-doc package and not the kernel-rt-doc package as distributed by Centos.
See How to fix? for Centos:7 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
iommu/amd: Wait for completion instead of returning early in iommu_completion_wait()
need_sync is a per-IOMMU flag shared by all domains and devices behind that IOMMU. It is set whenever a command is queued with sync == true and cleared when a completion-wait (CWAIT) command is queued. However, a cleared need_sync only means that a covering CWAIT has been queued, not that all previously queued commands have actually completed in hardware.
iommu_completion_wait() read need_sync locklessly and returned early when it was false. This breaks the "block until all previously queued commands have completed" contract in a multi-CPU scenario:
CPU2: queue inv-B => need_sync = true CPU1: queue CWAIT(N); need_sync = false; then wait_on_sem(N) CPU2: read need_sync == false => return 0 (no wait!)
CPU2 returns without waiting for any sequence number even though its inv-B may not have completed yet (CWAIT(N), queued after inv-B, has not been signaled). CPU2 then proceeds to, for example, free page-table pages while the IOMMU can still walk stale translations, opening a use-after-free window. This is a logical race in the meaning of the flag, not a memory-visibility issue, so barriers alone do not help.
Fix it without losing the optimization of avoiding redundant CWAIT commands: take iommu->lock before testing need_sync, and when it is false do not return early but wait for the last allocated sequence number (cmd_sem_val). Since need_sync == false implies no sync command was queued after the last CWAIT, that CWAIT is FIFO-ordered after every not-yet-completed command, so waiting for its sequence number guarantees all prior commands (possibly queued by another CPU) have completed. The common path with pending work is unchanged and no extra hardware command is issued.
References
- https://access.redhat.com/security/cve/CVE-2026-68329
- https://git.kernel.org/stable/c/02f8cefa2ad95ea3754f0cfd6fbae7f866202ccb
- https://git.kernel.org/stable/c/1e75a8255f11c81fb07e81e5029cfd75804350a0
- https://git.kernel.org/stable/c/93494bd446396c257fb589f59894577e96e406e2
- https://git.kernel.org/stable/c/ab7faf5a172ebfdc423ebb3eea4d472740de82f9
- https://git.kernel.org/stable/c/d053eb7e09e10cbdca3fca8b35c1017d438091b2