Out-of-bounds read in Linux kernel - CVE-2026-89723

Vulnerability details

The vulnerability allows a local user to trigger an out-of-bounds memory access.

The vulnerability exists due to improper deletion of an intermediate B-tree node in the NILFS2 block mapping implementation when truncating a file causes a B-tree mapping to collapse into a direct mapping. A local user can truncate a file to cause a residual B-tree node to be processed as a direct mapping entry and trigger an out-of-bounds memory access.

The residual node remains dirty in the B-tree node cache and can subsequently be processed by the log writer.

Affected software

How to mitigate CVE-2026-89723

External References

• https://git.kernel.org/stable/c/28362e8ce51377afdec1782e661e808328a10514
• https://git.kernel.org/stable/c/448636c745a3f3b8582a0b8ce718c890a11c0fa9
• https://git.kernel.org/stable/c/45662dedb8f272ef7f16e69f13424c4bd0399240
• https://git.kernel.org/stable/c/5d3783c451a546373662ee11ec17019273e68034

Related Security Bulletins

• Out-of-bounds read in Linux kernel nilfs2