Vulnerability in Kernel (CVE-2025-38638)

Summary

Vulnerability in Kernel (CVE-2025-38638). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.16.1 or later.

Original description

The description as published by the source.

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

ipv6: add a retry logic in net6_rt_notify()

inet6_rt_notify() can be called under RCU protection only.
This means the route could be changed concurrently
and rt6_fill_node() could return -EMSGSIZE.

Re-size the skb when this happens and retry, removing
one WARN_ON() that syzbot was able to trigger:

WARNING: CPU: 3 PID: 6291 at net/ipv6/route.c:6342 inet6_rt_notify+0x475/0x4b0 net/ipv6/route.c:6342
Modules linked in:
CPU: 3 UID: 0 PID: 6291 Comm: syz.0.77 Not tainted 6.16.0-rc7-syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:inet6_rt_notify+0x475/0x4b0 net/ipv6/route.c:6342
Code: fc ff ff e8 6d 52 ea f7 e9 47 fc ff ff 48 8b 7c 24 08 4c 89 04 24 e8 5a 52 ea f7 4c 8b 04 24 e9 94 fd ff ff e8 9c fe 84 f7 90 <0f> 0b 90 e9 bd fd ff ff e8 6e 52 ea f7 e9 bb fb ff ff 48 89 df e8
RSP: 0018:ffffc900035cf1d8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffc900035cf540 RCX: ffffffff8a36e790
RDX: ffff88802f7e8000 RSI: ffffffff8a36e9d4 RDI: 0000000000000005
RBP: ffff88803c230f00 R08: 0000000000000005 R09: 00000000ffffffa6
R10: 00000000ffffffa6 R11: 0000000000000001 R12: 00000000ffffffa6
R13: 0000000000000900 R14: ffff888032ea4100 R15: 0000000000000000
FS: 00007fac7b89a6c0(0000) GS:ffff8880d6a20000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fac7b899f98 CR3: 0000000034b3f000 CR4: 0000000000…

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-2025-38638 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.16.1 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-38638" on the vendor's site.

CVE-2025-38638 (Kernel)
Patched: 6.16.1 — 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 6.16.1.

🛡️ 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 6.16.1
```
ステージング環境で 6.16.1 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":"6.16.0"},{"fixed":"6.16.1"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-38638 linux-lts Fixed in: 6.18.35-r1