Apache Tomcat: Security constraints for default servlet ignored method (CVE-2026-55956)
Published Last modified Sources: Red Hat, BSI, OSV, CVE.org
What is affected, what to do
Improper 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.
Update tomcat to version 11.0.23, Tomcat to version 11.0.23.
- Affected
- Apache Tomcat
lte 11.0.0-M1..11.0.22 - Apache Tomcat
lte 10.1.0-M1..10.1.55 - Apache Tomcat
lte 9.0.0.M1..9.0.118 - Apache Tomcat
lte 8.5.0..8.5.100 - Apache Tomcat
lte 7.0.0..7.0.109
- Apache Tomcat
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Metrics
6.5
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
6.5
CVSS v3
Severity Medium on the scale from 0 to 10.
Source: Red Hat, BSI, OSV, CVE.org
0.7 %
EPSS score
Low — model estimates < 1% exploitation likelihood.
Source: FIRST EPSS, percentile 52.2
Show all metrics
- Severity
- Medium
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 74.60 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 6.5 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 6.5
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 0.7 %
- Low — model estimates < 1% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 52.2
- High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-285
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Improper 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.
Source: redhat_csaf, BSI WID Portal, BSI CSAF, OSV (Open Source Vulnerabilities), cvelistv5, NVD (NIST), CVE.org (MITRE)
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apache Software Foundation | Apache Tomcat |
|
|
| apache | tomcat |
|
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| Apache | Tomcat |
|
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| IBM | QRadar SIEM |
|
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| Oracle | Communications |
|
|
Weakness classes (CWE)
CWE-285Improper Authorization
Class
The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.
Entry at MITRE CWE-285
References & sources
- openwall.comlists/oss-security/2026/06/29/25web
- lists.apache.orgthread/dcjdcnnnww9hhdm016hr0l7hpw1bzjfpweb, Vendor advisory
- NVD (NIST)vuln/detail/CVE-2026-55956web
Reanalysis & status changes
Chronological NVD audit events for this CVE — reanalyses, CVSS updates, CPE diffs.
Initial Analysisnvd@nist.gov
- CPE Configuration: after OR *cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:* versions from (including) 10.1.0 up to (excluding) 10.1.56 *cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:* versions from (including) 11.0.0 up to (excluding) 11.0.23 *cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:* versions up to (excluding) 9.0.119
- Reference Type: after Apache Software Foundation: https://lists.apache.org/thread/dcjdcnnnww9hhdm016hr0l7hpw1bzjfp Types: Mailing List, Vendor Advisory
- Reference Type: after CVE: http://www.openwall.com/lists/oss-security/2026/06/29/25 Types: Third Party Advisory
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