Vulnerability in Kernel (CVE-2025-21873)

Summary

Vulnerability in Kernel (CVE-2025-21873). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.6.81, 6.12.18, 6.13.6 or later.

Original description

The description as published by the source.

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

scsi: ufs: core: bsg: Fix crash when arpmb command fails

If the device doesn't support arpmb we'll crash due to copying user data in
bsg_transport_sg_io_fn().

In the case where ufs_bsg_exec_advanced_rpmb_req() returns an error, do not
set the job's reply_len.

Memory crash backtrace:
3,1290,531166405,-;ufshcd 0000:00:12.5: ARPMB OP failed: error code -22

4,1308,531166555,-;Call Trace:

4,1309,531166559,-;

4,1310,531166565,-; ? show_regs+0x6d/0x80

4,1311,531166575,-; ? die+0x37/0xa0

4,1312,531166583,-; ? do_trap+0xd4/0xf0

4,1313,531166593,-; ? do_error_trap+0x71/0xb0

4,1314,531166601,-; ? usercopy_abort+0x6c/0x80

4,1315,531166610,-; ? exc_invalid_op+0x52/0x80

4,1316,531166622,-; ? usercopy_abort+0x6c/0x80

4,1317,531166630,-; ? asm_exc_invalid_op+0x1b/0x20

4,1318,531166643,-; ? usercopy_abort+0x6c/0x80

4,1319,531166652,-; __check_heap_object+0xe3/0x120

4,1320,531166661,-; check_heap_object+0x185/0x1d0

4,1321,531166670,-; __check_object_size.part.0+0x72/0x150

4,1322,531166679,-; __check_object_size+0x23/0x30

4,1323,531166688,-; bsg_transport_sg_io_fn+0x314/0x3b0

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-2025-21873 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.6.81, 6.12.18, 6.13.6 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-21873" on the vendor's site.

CVE-2025-21873 (Kernel)
Patched: 6.6.81, 6.12.18, 6.13.6 — 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 6.6.81, 6.12.18, 6.13.6.

🛡️ 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 6.6.81, 6.12.18, 6.13.6
```
ステージング環境で 6.6.81, 6.12.18, 6.13.6 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":"6.3.0"},{"fixed":"6.6.81"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.18"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.13.6"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-21873 linux-lts Fixed in: 6.12.41-r0
Debian DEBIAN-CVE-2025-21873 linux Fixed in: 6.12.19-1
Ubuntu UBUNTU-CVE-2025-21873 linux-hwe-edge