Summary

Vulnerability in Kernel (CVE-2023-53343). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 4.19.291, 5.4.251, 5.10.188, 5.15.121, 6.1.40, 6.4.5 or later.

Original description

The description as published by the source.

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

icmp6: Fix null-ptr-deref of ip6_null_entry->rt6i_idev in icmp6_dev().

With some IPv6 Ext Hdr (RPL, SRv6, etc.), we can send a packet that
has the link-local address as src and dst IP and will be forwarded to
an external IP in the IPv6 Ext Hdr.

For example, the script below generates a packet whose src IP is the
link-local address and dst is updated to 11::.

for f in $(find /proc/sys/net/ -name seg6_enabled); do echo 1 > $f; done

python3

from socket import *
from scapy.all import *

SRC_ADDR = DST_ADDR = "fe80::5054:ff:fe12:3456"

pkt = IPv6(src=SRC_ADDR, dst=DST_ADDR)
pkt /= IPv6ExtHdrSegmentRouting(type=4, addresses=["11::", "22::"], segleft=1)

sk = socket(AF_INET6, SOCK_RAW, IPPROTO_RAW)
sk.sendto(bytes(pkt), (DST_ADDR, 0))

For such a packet, we call ip6_route_input() to look up a route for the
next destination in these three functions depending on the header type.

ipv6_rthdr_rcv()
ipv6_rpl_srh_rcv()
ipv6_srh_rcv()

If no route is found, ip6_null_entry is set to skb, and the following
dst_input(skb) calls ip6_pkt_drop().

Finally, in icmp6_dev(), we dereference skb_rt6_info(skb)->rt6i_idev->dev
as the input device is the loopback interface. Then, we have to check if
skb_rt6_info(skb)->rt6i_idev is NULL or not to avoid NULL pointer deref
for ip6_null_entry.

BUG: kernel NULL pointer dereference, address: 0000000000000000…

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-2023-53343 has been found in Kernel.
Risk of unauthorized operations or information disclosure.
What to do: upgrade Kernel to 4.19.291, 5.4.251, 5.10.188, 5.15.121, 6.1.40, 6.4.5 or later.
If unsure, ask your IT team or search "Kernel CVE-2023-53343" on the vendor's site.

CVE-2023-53343 (Kernel)
Attack vector: local / no user interaction
Patched: 4.19.291, 5.4.251, 5.10.188, 5.15.121, 6.1.40, 6.4.5 — 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 4.19.291, 5.4.251, 5.10.188, 5.15.121, 6.1.40, 6.4.5.

🛡️ 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 4.19.291, 5.4.251, 5.10.188, 5.15.121, 6.1.40, 6.4.5
```
ステージング環境で 4.19.291, 5.4.251, 5.10.188, 5.15.121, 6.1.40, 6.4.5 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":"4.14.0"},{"fixed":"4.19.291"}]},{"type":"ECOSYSTEM","events":[{"introduced":"4.20.0"},{"fixed":"5.4.251"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.5.0"},{"fixed":"5.10.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.121"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.4.5"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

Debian DEBIAN-CVE-2023-53343 linux Fixed in: 5.10.191-1
Ubuntu UBUNTU-CVE-2023-53343 linux-azure