# CVE-2025-37807: bpf: Fix kmemleak warning for percpu hashmap

> A memory leak in the Linux kernel BPF subsystem can cause resource exhaustion and denial of service when kmemleak is enabled.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 8 May 2025
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-62729, AZL-69938, BELL-CVE-2025-37807, DEBIAN-CVE-2025-37807, GHSA-73cw-j3wh-rf6g, ROOT-OS-DEBIAN-11-CVE-2025-37807, ROOT-OS-DEBIAN-12-CVE-2025-37807, ROOT-OS-UBUNTU-2204-CVE-2025-37807, ROOT-OS-UBUNTU-2404-CVE-2025-37807, UBUNTU-CVE-2025-37807

## What is CVE-2025-37807?

CVE-2025-37807 is a medium-severity memory corruption vulnerability in Linux kernel, published on 8 May 2025. 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:

bpf: Fix kmemleak warning for percpu hashmap

Vlad Poenaru reported the following kmemleak issue:

  unreferenced object 0x606fd7c44ac8 (size 32):
    backtrace (crc 0):
      pcpu_alloc_noprof+0x730/0xeb0
      bpf_map_alloc_percpu+0x69/0xc0
      prealloc_init+0x9d/0x1b0
      htab_map_alloc+0x363/0x510
      map_create+0x215/0x3a0
      __sys_bpf+0x16b/0x3e0
      __x64_sys_bpf+0x18/0x20
      do_syscall_64+0x7b/0x150
      entry_SYSCALL_64_after_hwframe+0x4b/0x53

Further investigation shows the reason is due to not 8-byte aligned
store of percpu pointer in htab_elem_set_ptr():
  *(void __percpu **)(l->key + key_size) = pptr;

Note that the whole htab_elem alignment is 8 (for x86_64). If the key_size
is 4, that means pptr is stored in a location which is 4 byte aligned but
not 8 byte aligned. In mm/kmemleak.c, scan_block() scans the memory based
on 8 byte stride, so it won't detect above pptr, hence reporting the memory
leak.

In htab_map_alloc(), we already have

        htab->elem_size = sizeof(struct htab_elem) +
                          round_up(htab->map.key_size, 8);
        if (percpu)
                htab->elem_size += sizeof(void *);
        else
                htab->elem_size += round_up(htab->map.value_size, 8);

So storing pptr with 8-byte alignment won't cause any problem and can fix
kmemleak too.

The issue can be reproduced with bpf selftest as well:
  1. Enable CONFIG_DEBUG_KMEMLEAK config
  2. Add a getchar() before skel destroy in test_hash_map() in prog_tests/for_each.c.
     The purpose is to keep map available so kmemleak can be detected.
  3. run './test_progs -t for_each/hash_map &' and a kmemleak should be reported.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2025-37807?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-37807?

Apply the vendor's patch.

## Is CVE-2025-37807 being exploited?

There is no known exploitation of CVE-2025-37807 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-2025-37807 and fix it if it is affected.

What it is: CVE-2025-37807 is a medium-severity memory corruption vulnerability in Linux kernel, published on 8 May 2025. 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-2025-37807 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-2025-37807/ (Markdown: https://insights.sbomify.com/CVE-2025-37807/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-37807
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-37807
- OSV: https://osv.dev/vulnerability/CVE-2025-37807

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-37807/
Summaries are generated and may contain mistakes; the official description above is the record.