PT-2026-61344 · Linux · Linux

CVE-2026-64027 · Published 2026-07-19 · Updated 2026-07-19

Mitre

CVSS v3.1

7.8

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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

net: shaper: rework the VALID marking (again)

Recent commit changed the semantics from NOT VALID to VALID. I didn't realize that the flags are not stored atomically with the entry in XArray. There's still a race of reader observing a VALID mark for a slot, getting interrupted, writer replacing the entry with a different one, reader continuing, fetching the entry which is now a different pointer than the pointer for which VALID was meant.

The biggest consequence of this is that we may see a UAF since net shaper rollback() assumed that entries without VALID can be freed without observing RCU.

Looks like the XArray marks are buying us nothing at this point. Let's convert the code to an explicit valid field. The smp load acquire() / smp store release() barriers are marginally cleaner.

Fix

Related Identifiers

CVE-2026-64027

Affected Products

Linux

References · 4

• https://nvd.nist.gov/vuln/detail/CVE-2026-64027 · Security Note
• https://git.kernel.org/stable/c/96ea960dd40fd55302e0fd755176f26a95e6a50c · Note
• https://git.kernel.org/stable/c/b8d7519352ba8c6df83259295d4a3bad093cae90 · Note
• https://git.kernel.org/stable/c/2417df5e7bb4184b9d3a2988036bf2c46e594545 · Note