Vulnerability in tomcat (CVE-2026-55276)
Summary
Vulnerability in tomcat (CVE-2026-55276). Confidential information can be exposed externally. Mitigation: upgrade to 9.0.119, 10.1.56, 11.0.23 or later.
Original description
The description as published by the source.
Always-Incorrect Control Flow Implementation vulnerability in Apache Tomcat meant that special roles and empty authorisation constraints were not included when the effective web.xml was logged.
This issue affects Apache Tomcat: from 11.0.0 through 11.0.22, from 10.1.0 through 10.1.55, from 9.0.0 through 9.0.118, from 8.5.0 through 8.5.100. Other versions that have reached end of support may also be affected.
Users are recommended to upgrade to version 11.0.23, 10.1.56 or 9.0.119 which fixes the issue.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
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-2026-55276 has been found in tomcat.
Confidential information can be exposed externally. CVSS score: 9.1/10.
What to do: upgrade tomcat to 9.0.119, 10.1.56, 11.0.23 or later.
If unsure, ask your IT team or search "tomcat CVE-2026-55276" on the vendor's site.
CVE-2026-55276 (tomcat) — CWE-670 / CVSS v3 9.1
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 9.0.119, 10.1.56, 11.0.23 — 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.
A vulnerability (CWE-670) exists in tomcat.
Check the vendor advisory for the affected versions of tomcat.
Severity: Critical (CVSS 9.1/10). Confidential information can be exposed externally.
Update to 9.0.119, 10.1.56, 11.0.23.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'tomcat' . 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
-
1Identify exposure identify
grep -r 'tomcat' . | 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
tomcatを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade tomcat to 9.0.119, 10.1.56, 11.0.23ステージング環境で 9.0.119, 10.1.56, 11.0.23 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。
-
3Post-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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Ubuntu UBUNTU-CVE-2026-55276 tomcat6
References
- advisory lists.apache.org
- advisory openwall.com
- ATLASSIAN JSWSERVER-26934
- web nvd.nist.gov
- web github.com