# CVE-2026-99266: io_uring/zcrx: fix buffer offsets in areas above 4GB

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

In the Linux kernel, the following vulnerability has been resolved:

io_uring/zcrx: fix buffer offsets in areas above 4GB

io_zcrx_queue_cqe() computes the offset of the buffer in its area from
net_iov_idx(), which is an unsigned int, so the shift is done in 32 bits
and only the result is widened to the u64 that goes into the CQE. An area
can be up to 1TB in size. For every niov beyond the first 4GB the CQE
points the application at a buffer 4GB, or a multiple of that, below the
one which has the data. It reads the wrong data, and then returns a
buffer it doesn't own via the refill queue while the real one is never
given back.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 11ed914bbf948c4a37248f2876973ac18014056d; < 9bfb315e2d0907fbcaf5d0453dd6d873c9aa8d5b (affected, git); ≥ 11ed914bbf948c4a37248f2876973ac18014056d; < 51f4ee29bf0564e6ae7d3540693a9bc1dd2c8fd7 (affected, git). Source: CNA: Linux
- Linux / Linux: 6.15 (affected); ≥ 0; < 6.15 (unaffected, semver); ≥ 6.18.60; ≤ 6.18.* (unaffected, semver); ≥ 7.2.14; ≤ 7.2.* (unaffected, semver). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/9bfb315e2d0907fbcaf5d0453dd6d873c9aa8d5b (CNA: Linux)

- https://git.kernel.org/stable/c/51f4ee29bf0564e6ae7d3540693a9bc1dd2c8fd7 (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-99266; retrieved 2026-11-03; source updated 2026-11-03

Revision: 2856774908adecab29a6c627872c62d0d8423b052b245be5d30e5d0f5ec29b8d

Canonical: https://y2.dev/cve/CVE-2026-99266

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