Vulnerability in Kernel (CVE-2026-31636)

Summary

Vulnerability in Kernel (CVE-2026-31636). Confidential information can be exposed externally. Mitigation: upgrade to 6.18.23, 6.19.13 or later.

Original description

The description as published by the source.

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

rxrpc: fix RESPONSE authenticator parser OOB read

rxgk_verify_authenticator() copies auth_len bytes into a temporary
buffer and then passes p + auth_len as the parser limit to
rxgk_do_verify_authenticator(). Since p is a __be32 *, that inflates the
parser end pointer by a factor of four and lets malformed RESPONSE
authenticators read past the kmalloc() buffer.

Decoded from the original latest-net reproduction logs with
scripts/decode_stacktrace.sh:

BUG: KASAN: slab-out-of-bounds in rxgk_verify_response()
Call Trace:
dump_stack_lvl() [lib/dump_stack.c:123]
print_report() [mm/kasan/report.c:379 mm/kasan/report.c:482]
kasan_report() [mm/kasan/report.c:597]
rxgk_verify_response()
[net/rxrpc/rxgk.c:1103 net/rxrpc/rxgk.c:1167
net/rxrpc/rxgk.c:1274]
rxrpc_process_connection()
[net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364
net/rxrpc/conn_event.c:386]
process_one_work() [kernel/workqueue.c:3281]
worker_thread()
[kernel/workqueue.c:3353 kernel/workqueue.c:3440]
kthread() [kernel/kthread.c:436]
ret_from_fork() [arch/x86/kernel/process.c:164]

Allocated by task 54:
rxgk_verify_response()
[include/linux/slab.h:954 net/rxrpc/rxgk.c:1155
net/rxrpc/rxgk.c:1274]
rxrpc_process_connection()
[net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364
net/rxrpc/conn_event.c:386]

Convert the byte count to __be32 units before constructing the parser
limit.

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-2026-31636 has been found in Kernel.
Confidential information can be exposed externally.
What to do: upgrade Kernel to 6.18.23, 6.19.13 or later.
If unsure, ask your IT team or search "Kernel CVE-2026-31636" on the vendor's site.

CVE-2026-31636 (Kernel)
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 6.18.23, 6.19.13 — 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: ?. Confidential information can be exposed externally.

🔧 How to fix

Update to 6.18.23, 6.19.13.

🛡️ 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 6.18.23, 6.19.13
```
ステージング環境で 6.18.23, 6.19.13 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":"6.18.23"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.13"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

BellSoft Alpaquita BELL-CVE-2026-31636 linux-lts Fixed in: 6.18.35-r1
Debian DEBIAN-CVE-2026-31636 linux Fixed in: 6.19.13-1
Ubuntu UBUNTU-CVE-2026-31636 linux-hwe-edge