TomcatWeb server / proxy · Apache
CVE-2026-55956
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImproper Authorization vulnerability in Apache Tomcat leads to security constraints specified for the default servlet ignoring any method or method omission configured as part of the constraint. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.22, from 10.1.0-M1 through 10.1.55, from 9.0.0.M1 through 9.0.118, from 8.5.0 through 8.5.100, from 7.0.0 through 7.0.109. 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 fix the issue.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceApache Tomcat's default servlet fails to properly enforce security constraints configured for specific HTTP methods. When security constraints are defined for the default servlet, any method-level access controls or method omissions configured within those constraints are silently ignored, allowing attackers to bypass intended authorization restrictions.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
TomcatWeb server / proxy
< 9.0.119>= 10.1.0, < 10.1.56>= 11.0.0, < 11.0.23CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Identify installed Apache Tomcat versionCheck the server info by reading the $CATALINA_HOME/LICENSE file, or look at the serverinfo.properties in the Tomcat lib folder, or run: java -cp $CATALINA_HOME/lib/catalina.jar org.apache.catalina.util.ServerInfoAffected if The installed version is < 9.0.119, OR >= 10.1.0 and < 10.1.56, OR >= 11.0.0 and < 11.0.23
-
Locate web.xml configuration filesFind all web.xml files: the global $CATALINA_HOME/conf/web.xml and any application-level WEB-INF/web.xml files in deployed web applicationsAffected if Security constraints are defined that apply to the default servlet (/)
-
Inspect security constraints for default servletIn each web.xml found, look for <security-constraint> elements. Check if any <url-pattern> is / (the default servlet) or if constraints are applied at the root level without method-specific <http-method> or <http-method-omission> elementsAffected if Security constraints exist for the default servlet without explicit method-level restrictions, or with method omissions that may be ignored
-
Check for method-level access control configurationsWithin any security-constraint targeting the default servlet, examine if <http-method> elements (to restrict to specific methods) or <http-method-omission> elements (to restrict to all except specific methods) are presentAffected if Method-specific <http-method> or <http-method-omission> elements are configured but may be ignored due to the vulnerability
-
Verify security constraint behaviorTest access to the default servlet (root context /) with various HTTP methods (GET, POST, PUT, DELETE) against endpoints that should be restricted. If unauthenticated or unauthorized requests succeed when they should be denied based on method-specific constraints, the vulnerability is presentAffected if HTTP methods that should be denied based on security constraints are unexpectedly allowed
You are affected if your Tomcat version falls within the affected ranges AND you have security constraints configured for the default servlet with method-level restrictions or method omissions that may be bypassed.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped9.0.11910.1.5611.0.23
Upgrade Apache Tomcat to version 11.0.23, 10.1.56, or 9.0.119 which contain the fix for this improper authorization vulnerability.
Upgrade to Tomcat 9.0.119 (for 9.x branch), 10.1.56 (for 10.1.x branch), or 11.0.23 (for 11.x branch)
- 1. Identify your current Apache Tomcat version by checking the $CATALINA_HOME/RELEASE-NOTES file or running 'catalina.sh version'
- 2. Determine which branch you're on (9.x, 10.1.x, or 11.x) to select the appropriate fixed version
- 3. Download the fixed release: 9.0.119, 10.1.56, or 11.0.23 from https://tomcat.apache.org/
- 4. Back up your current Tomcat installation including all configuration files in the conf/ directory
- 5. Deploy the new Tomcat version in a staging environment and run your application test suite
- 6. Verify that security constraints with method-specific rules work correctly after the upgrade
- 7. Once validated, deploy the upgraded Tomcat to production
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Tomcat
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-55956 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-55956 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data