Apache Wicket: Incorrect Behavior Order: Early Validation (CVE-2026-84177)
Published Last modified Sources: BSI, CVE.org
What is affected, what to do
Incorrect behavior order in Apache Wicket: a file path is validated before the framework appends the attributes that complete it. org.apache.wicket.request.resource.PackageResource asks the configured package resource guard about a path built from the scope class' package and the file name in the request URL, and then hands that same path to the resource stream locator together with a style, a variation and a locale. Those three attributes are decoded from the name of the first query parameter and never appear in the string the guard was given. org.apache.wicket.core.util.resource.locator.ResourceNameIterator appends them to that path, each preceded by an underscore, in the order variation, style, locale, before the file extension, so the file that is opened is not the file the guard approved. org.apache.wicket.markup.html.PackageResourceGuard decides whether an HTML file is a component's markup template by looking for a class file of the same name beside it, stripping one underscore-delimited suffix at a time as it goes.
Update Wicket to version 9.25.0.
- Affected
- Apache Wicket
lte 8.0.0..8.19.0 - Apache Wicket
lte 9.0.0..9.24.0 - Apache Wicket
lte 10.0.0..10.11.0
- Apache Wicket
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Metrics
6.3
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: Vendor (CNA), CVSS v4
6.3
CVSS v4
Severity Medium on the scale from 0 to 10.
Source: BSI, CVE.org
—
EPSS score
No value is available for this vulnerability.
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- 61.50 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- 6.3 Methodology
CVSS v4
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- 6.3
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-179
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
Incorrect behavior order in Apache Wicket: a file path is validated before the framework appends the attributes that complete it. org.apache.wicket.request.resource.PackageResource asks the configured package resource guard about a path built from the scope class' package and the file name in the request URL, and then hands that same path to the resource stream locator together with a style, a variation and a locale. Those three attributes are decoded from the name of the first query parameter and never appear in the string the guard was given. org.apache.wicket.core.util.resource.locator.ResourceNameIterator appends them to that path, each preceded by an underscore, in the order variation, style, locale, before the file extension, so the file that is opened is not the file the guard approved. org.apache.wicket.markup.html.PackageResourceGuard decides whether an HTML file is a component's markup template by looking for a class file of the same name beside it, stripping one underscore-delimited suffix at a time as it goes. HTML is on the default allow list, so that check is the only thing separating a static HTML file, which may be served, from a markup template, which may not. Asked about the name of a template, the guard refuses it correctly. Asked about a shorter name for which no class exists, it accepts, and a style supplied in the URL then completes that name into the markup template of a component class, which is written to the response. An application is affected if the simple name of any of its component classes contains an underscore and no shorter part of that name is itself a class, such as Report_v2 or Wizard_Step1; an application with no such class name is not affected. No unusual deployment, packaging or configuration is required, and running in deployment rather than development mode does not prevent it. Java naming conventions discourage underscores in class names and no module Wicket ships has one, so no framework markup is exposed; what an application exposes this way is its own. A component whose class name has no underscore is not reachable, and neither is its localized or styled markup, because the guard finds the class file under the base name and refuses the request. The attributes cannot change the file extension and cannot leave the component's package, so nothing beyond HTML files in that package is reachable. Access is read-only, and what is disclosed is developer-authored template content: component structure, developer comments, markup that is rendered only under some conditions, inline script, and the endpoints a template names. No user data, credential or session material is reachable this way. An attacker has to name a class in the target package and the component itself, and Wicket writes fully qualified class names into the URL of every package resource it renders. This issue affects Apache Wicket: from 8.0.0 through 8.19.0, from 9.0.0 through 9.24.0, from 10.0.0 through 10.11.0. Users of Apache Wicket 7.x or older, which are no longer supported, should upgrade to a supported version. Users are recommended to upgrade to version 8.20.0, 9.25.0 or 10.12.0, which fix the issue.
Source: BSI CSAF, BSI WID Portal, NVD (NIST), cvelistv5
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Apache Software Foundation | Apache Wicket |
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| Apache | Wicket |
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Vendors and products
Weakness classes (CWE)
CWE-179Incorrect Behavior Order: Early Validation
Base
The product validates input before applying protection mechanisms that modify the input, which could allow an attacker to bypass the validation via dangerous inputs that only arise after the modification.
Entry at MITRE CWE-179
References & sources
- lists.apache.orgthread.html/hy089v60t5v36skpnbry96vr2427lw0oVendor advisory
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
ReceivedApache
CVSS V4.0: AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Weakness type: CWE-179
Description added or changed
Show 5 original changes
Individual changes of this event as published by NVD Type Action Before After Description added —Incorrect behavior order in Apache Wicket: a file path is validated before the framework appends the attributes that complete it. org.apache.wicket.request.resource.PackageResource asks the configured package resource guard about a path built from the scope class' package and the file name in the request URL, and then hands that same path to the resource stream locator together with a style, a variation and a locale. Those three attributes are decoded from the name of the first query parameter and never appear in the string the guard was given. org.apache.wicket.core.util.resource.locator.ResourceNameIterator appends them to that path, each preceded by an underscore, in the order variation, style, locale, before the file extension, so the file that is opened is not the file the guard approved. org.apache.wicket.markup.html.PackageResourceGuard decides whether an HTML file is a component's markup template by looking for a class file of the same name beside it, stripping one underscore-delimited suffix at a time as it goes. HTML is on the default allow list, so that check is the only thing separating a static HTML file, which may be served, from a markup template, which may not. Asked about the name of a template, the guard refuses it correctly. Asked about a shorter name for which no class exists, it accepts, and a style supplied in the URL then completes that name into the markup template of a component class, which is written to the response. An application is affected if the simple name of any of its component classes contains an underscore and no shorter part of that name is itself a class, such as Report_v2 or Wizard_Step1; an application with no such class name is not affected. No unusual deployment, packaging or configuration is required, and running in deployment rather than development mode does not prevent it. Java naming conventions discourage underscores in class names and no module Wicket ships has one, so no framework markup is exposed; what an application exposes this way is its own. A component whose class name has no underscore is not reachable, and neither is its localized or styled markup, because the guard finds the class file under the base name and refuses the request. The attributes cannot change the file extension and cannot leave the component's package, so nothing beyond HTML files in that package is reachable. Access is read-only, and what is disclosed is developer-authored template content: component structure, developer comments, markup that is rendered only under some conditions, inline script, and the endpoints a template names. No user data, credential or session material is reachable this way. An attacker has to name a class in the target package and the component itself, and Wicket writes fully qualified class names into the URL of every package resource it renders. This issue affects Apache Wicket: from 8.0.0 through 8.19.0, from 9.0.0 through 9.24.0, from 10.0.0 through 10.11.0. Users of Apache Wicket 7.x or older, which are no longer supported, should upgrade to a supported version. Users are recommended to upgrade to version 8.20.0, 9.25.0 or 10.12.0, which fix the issue.CVSS added —AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XWeakness type (CWE) added —CWE-179Affected versions (publisher) added —New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/84xxx/CVE-2026-84177.json">CVE-2026-84177</a>Reference added —https://lists.apache.org/thread.html/hy089v60t5v36skpnbry96vr2427lw0oSource identifier: security@apache.org
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