CVE-2026-99266

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    CVE-2026-99266

    Published: 3 Nov 2026Last Modified: 4 Nov 2026

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

    Details: 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.

    References: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git, https://git.kernel.org/stable/c/51f4ee29bf0564e6ae7d3540693a9bc1dd2c8fd7, https://git.kernel.org/stable/c/9bfb315e2d0907fbcaf5d0453dd6d873c9aa8d5b, https://git.kernel.org/stable/c/ab4536bf2e5617b04f2d9396f06393c7bbfb071d, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99266.json, https://nvd.nist.gov/vuln/detail/CVE-2026-99266

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 11ed914bbf948c4a37248f2876973ac18014056d
    Fixed -9bfb315e2d0907fbcaf5d0453dd6d873c9aa8d5b

    Affected versions

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2026-99266 | CVE-DB