CVE-2026-23230
In the Linux kernel, the following vulnerability has been resolved: smb: client: split cached_fid bitfields to avoid shared-byte RMW races is_open, has_lease and on_list are stored in the same bitfield byte in struct cached_fid but are updated in…
Does this matter?
Lower severity and a low EPSS score (0.22%). Track it; it rarely justifies an emergency change on its own.
Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: split cached_fid bitfields to avoid shared-byte RMW races is_open, has_lease and on_list are stored in the same bitfield byte in struct cached_fid but are updated in different code paths that may run concurrently. Bitfield assignments generate byte read–modify–write operations (e.g. `orb $mask, addr` on x86_64), so updating one flag can restore stale values of the others. A possible interleaving is: CPU1: load old byte (has_lease=1, on_list=1) CPU2: clear both flags (store 0) CPU1: RMW store (old | IS_OPEN) -> reintroduces cleared bits To avoid this class of races, convert these flags to separate bool fields.
- CVSS 3.1
- 5.5 MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.22% probability · 12th percentile
- CISA KEV
- Not listed
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/3eaa22d688311c708b73f3c68bc6d0c8e3f0f77aPatch
- https://git.kernel.org/stable/c/4386f6af8aaedd0c5ad6f659b40cadcc8f423828Patch
- https://git.kernel.org/stable/c/4cfa4c37dcbcfd70866e856200ed8a2894cac578Patch
- https://git.kernel.org/stable/c/569fecc56bfe4df66f05734d67daef887746656bPatch
- https://git.kernel.org/stable/c/c4b9edd55987384a1f201d3d07ff71e448d79c1bPatch
- https://git.kernel.org/stable/c/ec306600d5ba7148c9dbf8f5a8f1f5c1a044a241Patch
- https://cert-portal.siemens.com/productcert/html/ssa-253495.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.