CVE-2026-80811 Linux CVE debrief

Who should care

Linux system administrators, security teams, and developers working with io_uring workloads should assess exposure and prioritize patching. They should verify Linux kernel versions, prioritize patching for systems with io_uring workloads, and assess cache configuration and recycling for io_async_cmd. Additionally, they should review compensating controls for exposed systems, check relevant monitoring and logs, and track exceptions and retest remediated

Why it matters

CVE-2026-80811 is a Linux kernel vulnerability that allows for an io_async_cmd iovec leak when the async cmd is not recycled. This issue arises from inadequate freeing of the iovec array in certain paths, particularly when the cache is full and io_alloc_cache_put() fails. Linux system administrators, security teams, and developers working with io_uring workloads should assess exposure and prioritize patching.

• Verify Linux kernel versions for exposure to CVE-2026-80811
• Prioritize patching for systems with io_uring workloads
• Assess cache configuration and recycling for io_async_cmd

Technical summary

The Linux kernel vulnerability CVE-2026-80811 allows for an io_async_cmd iovec leak when the async cmd is not recycled. This issue arises from inadequate freeing of the iovec array in certain paths, particularly when the cache is full and io_alloc_cache_put() fails. The leak is caused by the io_uring_cmd_prep() function not flagging an inherited vec for freeing. io_clean_op()'s kfree(req->async_data) drops the io_async_cmd without it. io_req_uring_cleanup() clears the async data flags only when io_alloc_cache_put() succeeds, and the cache holds IO_ALLOC_CACHE_MAX == 128 entries, so once it is full the put fails and the vec is left behind.

Defensive priority

Assess exposure and verify Linux kernel versions; prioritize patching for io_uring workloads.

Recommended defensive actions

• Assess Linux kernel versions for exposure to CVE-2026-80811
• Prioritize patching for systems with io_uring workloads
• Verify cache configuration and recycling for io_async_cmd
• 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 Linux kernel vulnerability allows for an io_async_cmd iovec leak when the async cmd is not recycled. This issue arises from inadequate freeing of the iovec array in certain paths, particularly when the cache is full and io_alloc_cache_put() fails.

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.