Out-of-bounds read in Linux kernel - CVE-2026-89574

Vulnerability details

The vulnerability allows a local user to read beyond the dm-bufio buffer.

The vulnerability exists due to improper validation of on-disk array block headers in the dm-array component when loading dm-cache mappings from on-disk array blocks. A local user can cause dm_cache_load_mappings() to process an array block header whose entry count exceeds its capacity to read beyond the dm-bufio buffer.

The vulnerable path is reached during dm-cache activation.

Affected software

How to mitigate CVE-2026-89574

External References

• https://git.kernel.org/stable/c/2965787723084835b18dfe993cd450ebf5bd4540
• https://git.kernel.org/stable/c/67adda7ed5da3e3b64f5b9021a02c21fb374fd9c
• https://git.kernel.org/stable/c/9808ddffb4bc659352df3020cd84d9d864820ee5
• https://git.kernel.org/stable/c/b33f76d33aaeacf3baf3370d8d64985169b36600

Related Security Bulletins

• Out-of-bounds read in Linux kernel md persistent-data driver