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

> A use-after-free vulnerability in the Linux kernel iomap subsystem allows attackers to cause denial of service or potentially execute code via invalid folio access.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Apr 2026
- **Updated:** 5 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-31463, GHSA-rprr-w46r-7762, UBUNTU-CVE-2026-31463

## 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: Linux kernel.

## How do I fix CVE-2026-31463?

Apply the vendor's patch.

## 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](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31463 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-31463 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-31463/ (Markdown: https://insights.sbomify.com/CVE-2026-31463/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31463
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31463
- OSV: https://osv.dev/vulnerability/CVE-2026-31463

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31463/
Summaries are generated and may contain mistakes; the official description above is the record.