CVE-2026-23230: smb: client: split cached_fid bitfields to avoid shared-byte RMW races
In the Linux kernel, the following vulnerability has been resolved:
smb: client: split cachedfid bitfields to avoid shared-byte RMW races
isopen, haslease and onlist are stored in the same bitfield byte in struct cachedfid 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 x8664), so updating one flag can restore stale values of the others.
A possible interleaving is: CPU1: load old byte (haslease=1, onlist=1) CPU2: clear both flags (store 0) CPU1: RMW store (old | ISOPEN) -> reintroduces cleared bits
To avoid this class of races, convert these flags to separate bool fields.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-23230?
CVE-2026-23230 has a high severity rating due to its potential to allow remote memory write races.
How do I fix CVE-2026-23230?
To fix CVE-2026-23230, upgrade to the latest version of the Linux kernel that includes the patch.
What systems are affected by CVE-2026-23230?
CVE-2026-23230 affects systems running vulnerable versions of the Linux kernel with SMB client capabilities.
What are the potential impacts of CVE-2026-23230?
Exploitation of CVE-2026-23230 could lead to data corruption and system instability.
Is there a workaround for CVE-2026-23230?
Currently, there are no effective workarounds for CVE-2026-23230 apart from applying the security patch.