CVE-2026-64264 Affecting kernel6.18-tools-debuginfo package, versions <1:6.18.39-79.141.amzn2023


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.15% (6th percentile)

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  • Snyk IDSNYK-AMZN2023-KERNEL618TOOLSDEBUGINFO-18907999
  • published18 Aug 2026
  • disclosed25 Jul 2026

Introduced: 25 Jul 2026

NewCVE-2026-64264  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 kernel6.18-tools-debuginfo to version 1:6.18.39-79.141.amzn2023 or higher.
This issue was patched in ALAS2023-2026-2045.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel6.18-tools-debuginfo package and not the kernel6.18-tools-debuginfo package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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

fuse-uring: fix EFAULT clobber in fuse_uring_commit

copy_from_user() returns the number of bytes not copied as an unsigned residual on failure (1..sizeof(struct fuse_out_header)). fuse_uring_commit stores that residual in ssize_t err, sets req->out.h.error to -EFAULT, then jumps to out: with err still holding the positive residual.

err = copy_from_user(&amp;req-&gt;out.h, &amp;ent-&gt;headers-&gt;in_out,
                     sizeof(req-&gt;out.h));
if (err) {
    req-&gt;out.h.error = -EFAULT;
    goto out;          /* err is the positive residual */
}
...
out:
    fuse_uring_req_end(ent, req, err);

fuse_uring_req_end() then runs

if (error)
    req-&gt;out.h.error = error;

which overwrites the just-assigned -EFAULT with the positive residual. FUSE callers such as fuse_simple_request() test err < 0 to detect failure, so the positive value is interpreted as success and the caller proceeds with an uninitialised or partial req->out.args.

Fix by assigning err = -EFAULT in the failure branch before jumping to out, so fuse_uring_req_end() receives a negative errno and sets req->out.h.error to -EFAULT.

CVSS Base Scores

version 3.1