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CVE-2026-23397 high CVSS 7.1

Out-of-Bounds Read in Kernel (CVE-2026-23397)

Summary

Vulnerability in Kernel (CVE-2026-23397). Confidential information can be exposed externally. Mitigation: upgrade to 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10 or later.

Original description

The description as published by the source.

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

nfnetlink_osf: validate individual option lengths in fingerprints

nfnl_osf_add_callback() validates opt_num bounds and string
NUL-termination but does not check individual option length fields.
A zero-length option causes nf_osf_match_one() to enter the option
matching loop even when foptsize sums to zero, which matches packets
with no TCP options where ctx->optp is NULL:

Oops: general protection fault
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:nf_osf_match_one (net/netfilter/nfnetlink_osf.c:98)
Call Trace:
nf_osf_match (net/netfilter/nfnetlink_osf.c:227)
xt_osf_match_packet (net/netfilter/xt_osf.c:32)
ipt_do_table (net/ipv4/netfilter/ip_tables.c:293)
nf_hook_slow (net/netfilter/core.c:623)
ip_local_deliver (net/ipv4/ip_input.c:262)
ip_rcv (net/ipv4/ip_input.c:573)

Additionally, an MSS option (kind=2) with length < 4 causes
out-of-bounds reads when nf_osf_match_one() unconditionally accesses
optp[2] and optp[3] for MSS value extraction. While RFC 9293
section 3.2 specifies that the MSS option is always exactly 4
bytes (Kind=2, Length=4), the check uses "< 4" rather than
"!= 4" because lengths greater than 4 do not cause memory
safety issues -- the buffer is guaranteed to be at least
foptsize bytes by the ctx->optsize == foptsize check.

Reject fingerprints where any option has zero length, or where an MSS
option has length less than 4, at add time rat…

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory 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-2026-23397 has been found in Kernel.
Confidential information can be exposed externally. CVSS score: 7.1/10.
What to do: upgrade Kernel to 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10 or later.
If unsure, ask your IT team or search "Kernel CVE-2026-23397" on the vendor's site.

CVE-2026-23397 (Kernel) — CWE-125 / CVSS v3 7.1
Attack vector: local / no user interaction
Patched: 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10 — 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

Out-of-bounds read (CWE-125) exists in Kernel.

📍 Affected scope

Check the vendor advisory for the affected versions of Kernel.

🔥 Severity

Severity: High (CVSS 7.1/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10.

🛡️ 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. 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. 2
    Apply patch patch 
    Upgrade Kernel to 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10

    ステージング環境で 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10 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. 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":"2.6.31"},{"fixed":"5.10.253"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.203"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.167"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.130"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.78"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.20"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.10"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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