CVE-2026-31438 netfs: Fix kernel BUG in netfs_limit_iter() for ITER_KVEC iterators

What is CVE-2026-31438?

CVE-2026-31438 is a medium-severity vulnerability in Linux kernel, published on 22 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

netfs: Fix kernel BUG in netfs_limit_iter() for ITER_KVEC iterators

When a process crashes and the kernel writes a core dump to a 9P filesystem, __kernel_write() creates an ITER_KVEC iterator. This iterator reaches netfs_limit_iter() via netfs_unbuffered_write(), which only handles ITER_FOLIOQ, ITER_BVEC and ITER_XARRAY iterator types, hitting the BUG() for any other type.

Fix this by adding netfs_limit_kvec() following the same pattern as netfs_limit_bvec(), since both kvec and bvec are simple segment arrays with pointer and length fields. Dispatch it from netfs_limit_iter() when the iterator type is ITER_KVEC.

Weakness: CWE-476

Which versions are affected by CVE-2026-31438?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-31438?

Apply the vendor's patch.

Is CVE-2026-31438 being exploited?

There is no known exploitation of CVE-2026-31438 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-31438, DEBIAN-CVE-2026-31438, GHSA-3jp7-x2f9-j2c3, ROOT-OS-DEBIAN-13-CVE-2026-31438, ROOT-OS-UBUNTU-2404-CVE-2026-31438, UBUNTU-CVE-2026-31438.