CVE-2026-90182 Linux CVE debrief

Who should care

Defenders responsible for Linux kernel maintenance, block-cgroup configurations, and systems using blk-iocost should assess exposure and prioritize verification of Linux kernel versions.

Why it matters

A vulnerability in the Linux kernel's blk-iocost has been resolved, but verification of Linux kernel versions and blk-iocost configurations is necessary to ensure correct congestion markings and prevent potential issues with page readahead, swap rate throttling, and anonymous folio allocation.

• Verification of Linux kernel versions and blk-iocost configurations is necessary to ensure correct congestion markings
• Incorrect congestion markings could affect page readahead, swap rate throttling, and anonymous folio allocation
• Defenders should prioritize applying necessary fixes from Linux kernel updates

Technical summary

The Linux kernel's blk-iocost did not clear the delay state when freeing policy data. This could lead to incorrect congestion markings for block-cgroup and its descendants, affecting page readahead, swap rate throttling, and anonymous folio allocation. The issue arises from iocg_kick_delay() turning sufficiently large debt into an explicit block-cgroup delay with blkcg_set_delay(), setting blkg->use_delay to -1 and incrementing blkcg->congestion_count. Clearing it again depends on iocg_kick_delay() running from the period timer, the waitq timer or the issue path. ioc_pd_free() removes the iocg from active_iocgs and cancels its waitq timer, and no further bios can arrive, so once it has run nothing is left which

Defensive priority

Defenders should assess exposure and prioritize verification of Linux kernel versions, especially those using blk-iocost, to ensure they have applied the necessary fixes.

Recommended defensive actions

• Assess exposure by verifying Linux kernel versions, especially those using blk-iocost
• Prioritize verification of congestion markings for block-cgroup and its descendants
• Apply necessary fixes from Linux kernel updates
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability and its resolution in the Linux kernel. However, the corpus does not establish versions, exploitation, impact, or remediation beyond vendor-provided information.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.