# CVE-2025-71110: mm/slub: reset KASAN tag in defer_free() before accessing freed memory

> A use-after-free bug in the Linux kernel SLUB allocator triggers KASAN reports and potential crashes when CONFIG_SLUB_TINY and ARM64 MTE are enabled.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Jan 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-71110, GHSA-m8f2-rw7m-jrxf, UBUNTU-CVE-2025-71110

## What is CVE-2025-71110?

CVE-2025-71110 is a high-severity use after free vulnerability in Linux kernel, published on 14 Jan 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:

mm/slub: reset KASAN tag in defer_free() before accessing freed memory

When CONFIG_SLUB_TINY is enabled, kfree_nolock() calls kasan_slab_free()
before defer_free(). On ARM64 with MTE (Memory Tagging Extension),
kasan_slab_free() poisons the memory and changes the tag from the
original (e.g., 0xf3) to a poison tag (0xfe).

When defer_free() then tries to write to the freed object to build the
deferred free list via llist_add(), the pointer still has the old tag,
causing a tag mismatch and triggering a KASAN use-after-free report:

  BUG: KASAN: slab-use-after-free in defer_free+0x3c/0xbc mm/slub.c:6537
  Write at addr f3f000000854f020 by task kworker/u8:6/983
  Pointer tag: [f3], memory tag: [fe]

Fix this by calling kasan_reset_tag() before accessing the freed memory.
This is safe because defer_free() is part of the allocator itself and is
expected to manipulate freed memory for bookkeeping purposes.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2025-71110?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-71110?

Apply the vendor's patch.

## Is CVE-2025-71110 being exploited?

There is no known exploitation of CVE-2025-71110 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-2025-71110 and fix it if it is affected.

What it is: CVE-2025-71110 is a high-severity use after free vulnerability in Linux kernel, published on 14 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-71110 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-2025-71110/ (Markdown: https://insights.sbomify.com/CVE-2025-71110/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-71110
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-71110
- OSV: https://osv.dev/vulnerability/CVE-2025-71110

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-71110/
Summaries are generated and may contain mistakes; the official description above is the record.