Vulnerability in Kernel (CVE-2025-21737)

Summary

Vulnerability in Kernel (CVE-2025-21737). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.12.14, 6.13.3 or later.

Original description

The description as published by the source.

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

ceph: fix memory leak in ceph_mds_auth_match()

We now free the temporary target path substring allocation on every
possible branch, instead of omitting the default branch. In some
cases, a memory leak occured, which could rapidly crash the system
(depending on how many file accesses were attempted).

This was detected in production because it caused a continuous memory
growth, eventually triggering kernel OOM and completely hard-locking
the kernel.

Relevant kmemleak stacktrace:

unreferenced object 0xffff888131e69900 (size 128):
  comm "git", pid 66104, jiffies 4295435999
  hex dump (first 32 bytes):
    76 6f 6c 75 6d 65 73 2f 63 6f 6e 74 61 69 6e 65  volumes/containe
    72 73 2f 67 69 74 65 61 2f 67 69 74 65 61 2f 67  rs/gitea/gitea/g
  backtrace (crc 2f3bb450):
    [] __kmalloc_noprof+0x359/0x510
    [] ceph_mds_check_access+0x5bf/0x14e0 [ceph]
    [] ceph_open+0x312/0xd80 [ceph]
    [] do_dentry_open+0x456/0x1120
    [] vfs_open+0x79/0x360
    [] path_openat+0x1de5/0x4390
    [] do_filp_open+0x19c/0x3c0
    [] do_sys_openat2+0x141/0x180
    [] __x64_sys_open+0xe5/0x1a0
    [] do_syscall_64+0xb7/0x210
    [] entry_SYSCALL_64_after_hwframe+0x77/0x7f

It can be triggered by mouting a subdirectory of a CephFS filesystem,
and then trying to access files on this subdirectory with an auth token
using a path-scoped capability:

$ ceph au…

Source: OSV.dev (Open Source Vulnerabilities) NVD OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2025-21737 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.12.14, 6.13.3 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-21737" on the vendor's site.

CVE-2025-21737 (Kernel)
Attack vector: local / no user interaction
Patched: 6.12.14, 6.13.3 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (unclassified) exists in Kernel.

📍 Affected scope

Check the vendor advisory for the affected versions of Kernel.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 6.12.14, 6.13.3.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Kernel' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
grep -r 'Kernel' . | grep -v node_modules
```
リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で Kernel を grep し、稼働しているサービス・バージョンを把握する。
2
Apply patch patch
```
Upgrade Kernel to 6.12.14, 6.13.3
```
ステージング環境で 6.12.14, 6.13.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
3
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Linux Kernel

[{"type":"ECOSYSTEM","events":[{"introduced":"6.10.0"},{"fixed":"6.12.14"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.13.3"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-21737 linux-lts Fixed in: 6.12.41-r0
Debian DEBIAN-CVE-2025-21737 linux Fixed in: 6.12.15-1