High [CVE-2026-64267] avoid 32-bit prune notification count wrap
This high-severity Red Hat Linux advisory covers CVE-2026-64267 affecting Red Hat Enterprise Linux 6, Red Hat package: kernel.
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Summary
In the Linux kernel, the following vulnerability has been resolved: fuse: avoid 32-bit prune notification count wrap FUSE_NOTIFY_PRUNE validates the nodeid payload length with: size - sizeof(outarg)!= outarg.count * sizeof(u64) On 32-bit kernels, size_t is also 32 bits, so the daemon-controlled count multiplication can wrap.
A prune notification with count 0x20000000 and no nodeid payload passes the check, enters the copy loop, and asks the device copy path to read nodeids that are not present in the userspace write buffer. In QEMU this reaches the fuse_copy_fill() BUG_ON(!err) path.
Validate the payload length with array_size() instead. That accepts exactly the same valid messages, but avoids wrapping arithmetic before the copy loop consumes the count.
A flaw was found in the Linux kernel's Filesystem in Userspace (FUSE) component. On 32-bit systems, an integer overflow vulnerability exists in the handling of `FUSE_NOTIFY_PRUNE` messages.
A malicious FUSE daemon or a local user could craft a prune notification with a specific count, causing an integer overflow during payload length validation. This can lead to the kernel attempting to read non-existent data, resulting in a system crash and a Denial of Service (DoS).
Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-190.
Affected Red Hat products: Red Hat Enterprise Linux 6.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 10 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 10 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 10 days ago·verify at source
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