Vulnerability in Kernel (CVE-2025-39852)

Summary

Vulnerability in Kernel (CVE-2025-39852). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.12.46, 6.16.6 or later.

Original description

The description as published by the source.

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

net/tcp: Fix socket memory leak in TCP-AO failure handling for IPv6

When tcp_ao_copy_all_matching() fails in tcp_v6_syn_recv_sock() it just
exits the function. This ends up causing a memory-leak:

unreferenced object 0xffff0000281a8200 (size 2496):
comm "softirq", pid 0, jiffies 4295174684
hex dump (first 32 bytes):
7f 00 00 06 7f 00 00 06 00 00 00 00 cb a8 88 13 ................
0a 00 03 61 00 00 00 00 00 00 00 00 00 00 00 00 ...a............
backtrace (crc 5ebdbe15):
kmemleak_alloc+0x44/0xe0
kmem_cache_alloc_noprof+0x248/0x470
sk_prot_alloc+0x48/0x120
sk_clone_lock+0x38/0x3b0
inet_csk_clone_lock+0x34/0x150
tcp_create_openreq_child+0x3c/0x4a8
tcp_v6_syn_recv_sock+0x1c0/0x620
tcp_check_req+0x588/0x790
tcp_v6_rcv+0x5d0/0xc18
ip6_protocol_deliver_rcu+0x2d8/0x4c0
ip6_input_finish+0x74/0x148
ip6_input+0x50/0x118
ip6_sublist_rcv+0x2fc/0x3b0
ipv6_list_rcv+0x114/0x170
__netif_receive_skb_list_core+0x16c/0x200
netif_receive_skb_list_internal+0x1f0/0x2d0

This is because in tcp_v6_syn_recv_sock (and the IPv4 counterpart), when
exiting upon error, inet_csk_prepare_forced_close() and tcp_done() need
to be called. They make sure the newsk will end up being correctly
free'd.

tcp_v4_syn_recv_sock() makes this very clear by having the put_and_exit
label that takes care of things. So, this patch here makes sure
tcp_v4_syn_recv_sock and tcp_v6_…

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-2025-39852 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 6.12.46, 6.16.6 or later.
If unsure, ask your IT team or search "Kernel CVE-2025-39852" on the vendor's site.

CVE-2025-39852 (Kernel)
Attack vector: local / no user interaction
Patched: 6.12.46, 6.16.6 — 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 6.12.46, 6.16.6.

🛡️ 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 6.12.46, 6.16.6
```
ステージング環境で 6.12.46, 6.16.6 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":"6.7.0"},{"fixed":"6.12.46"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.16.6"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2025-39852 linux-lts Fixed in: 6.12.51-r0
Debian DEBIAN-CVE-2025-39852 linux Fixed in: 6.12.48-1
Ubuntu UBUNTU-CVE-2025-39852 linux-hwe-edge