Vulnerability in gawk (UBUNTU-CVE-2026-40468)

Summary

Vulnerability in gawk (UBUNTU-CVE-2026-40468). Data can be tampered with by attackers. Mitigation: upgrade to 1:4.0.1+dfsg-2.1ubuntu2+esm2 or later.

Original description

The description as published by the source.

Integer overflow vulnerability has been found in "builtin.c" program file of gawk. This issue may lead to memory exhaustion on the hosting operating system and could be used to overwrite gawk heap metadata and objects with attacker-controlled bytes. It affects gawk in versions 5.4.0 and below.

Source: OSV.dev (Open Source Vulnerabilities) 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 UBUNTU-CVE-2026-40468 has been found in gawk.
Data can be tampered with by attackers.
What to do: upgrade gawk to 1:4.0.1+dfsg-2.1ubuntu2+esm2 or later.
If unsure, ask your IT team or search "gawk UBUNTU-CVE-2026-40468" on the vendor's site.

UBUNTU-CVE-2026-40468 (gawk)
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1:4.0.1+dfsg-2.1ubuntu2+esm2 — 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 gawk.

📍 Affected scope

Check the vendor advisory for the affected versions of gawk.

🔥 Severity

Severity: ?. Data can be tampered with by attackers.

🔧 How to fix

Update to 1:4.0.1+dfsg-2.1ubuntu2+esm2.

🛡️ 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 'gawk' . 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 'gawk' . | 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 gawk 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 gawk to 1:4.0.1+dfsg-2.1ubuntu2+esm2
```
ステージング環境で 1:4.0.1+dfsg-2.1ubuntu2+esm2 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

Ubuntu:Pro:14.04:LTS gawk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:4.0.1+dfsg-2.1ubuntu2+esm2"}]}]

Ubuntu:Pro:16.04:LTS gawk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:4.1.3+dfsg-0.1ubuntu0.1~esm2"}]}]

Ubuntu:Pro:18.04:LTS gawk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:4.1.4+dfsg-1ubuntu0.1~esm2"}]}]

Ubuntu:Pro:20.04:LTS gawk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:5.0.1+dfsg-1ubuntu0.1+esm1"}]}]

Ubuntu:22.04:LTS gawk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:5.1.0-1ubuntu0.2"}]}]

Ubuntu:24.04:LTS gawk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:5.2.1-2ubuntu0.1"}]}]

Ubuntu:26.04:LTS gawk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1:5.3.2-1ubuntu1.1"}]}]

References

advisory ubuntu.com
report ubuntu.com
report cve.org