CVE-2026-31463 iomap: fix invalid folio access when i_blkbits differs from I/O granularity

What is CVE-2026-31463?

CVE-2026-31463 is a critical use after free vulnerability in Linux kernel, published on 22 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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

iomap: fix invalid folio access when i_blkbits differs from I/O granularity

Commit aa35dd5cbc06 ("iomap: fix invalid folio access after folio_end_read()") partially addressed invalid folio access for folios without an ifs attached, but it did not handle the case where 1 << inode->i_blkbits matches the folio size but is different from the granularity used for the IO, which means IO can be submitted for less than the full folio for the !ifs case.

In this case, the condition:

if (*bytes_submitted == folio_len) ctx->cur_folio = NULL;

in iomap_read_folio_iter() will not invalidate ctx->cur_folio, and iomap_read_end() will still be called on the folio even though the IO helper owns it and will finish the read on it.

Fix this by unconditionally invalidating ctx->cur_folio for the !ifs case.

Which versions are affected by CVE-2026-31463?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-31463?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2026-31463 being exploited?

There is no known exploitation of CVE-2026-31463 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 DEBIAN-CVE-2026-31463, GHSA-rprr-w46r-7762, UBUNTU-CVE-2026-31463.