EUVD-2026-67774
GHSA-7qwg-675j-8j75
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessCompromise or obtain site manager/admin credentials
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DeliveryLog in and configure custom navigation URL to javascript: payload
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ExploitVictim visits Omeka S site
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ExecutionVictim clicks malicious navigation link
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PersistBrowser executes attacker JavaScript
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ImpactSession token or credential exfiltration
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK
2 techniques across 2 tactics: Initial Access, Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires two preconditions: first, the attacker must have Omeka S site manager or administrator-level access to configure site navigation custom URLs (a privileged operation, contradicting the PR:N in the published CVSS vector); second, a victim user must actively click the malicious navigation link (UI:R is accurately reflected). The attack is further limited to Omeka S deployments that use the custom URL navigation link type - sites that use only internal page links or do not expose site navigation editing to multiple accounts are not meaningfully exposed. The vulnerability does not affect server-side data and cannot be triggered without victim interaction. |
| Impact | The published CVSS score of 6.1 (Medium) uses AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N. The PR:N rating warrants scrutiny: exploitation requires that a user with site manager or administrator privileges first configure the malicious navigation URL - making the effective attacker prerequisite closer to PR:H than PR:N. This significantly reduces real-world risk compared to a raw reading of the CVSS score. The S:C (scope change) reflects that the impact is on the visitor's browser rather than the server itself. EPSS data was not provided, and this CVE is absent from the CISA KEV catalog, indicating no confirmed active exploitation. A researcher writeup (raav3n/vulnerability-research) exists, but no standalone exploit code was identified. The missing NVD CPE string means automated vulnerability scanners will not reliably flag affected instances, creating a blind spot for asset inventory. For organizations running Omeka S in public-facing deployments with multiple site managers, the risk is real but bounded - the attack surface shrinks considerably in single-administrator deployments. |
| Exploit ScenarioDerived | An attacker who has obtained Omeka S site manager or administrator credentials - through phishing, credential reuse, or account compromise - configures a site navigation custom URL link with a |
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Alert meAnalysisAIv1 – Aug 28, 2026
Cross-site scripting via javascript: URI injection in Omeka S 4.2.0 allows an attacker who controls site navigation configuration to plant a malicious custom URL that executes arbitrary JavaScript in any visitor's browser when the navigation link is clicked. The flaw resides in the Url.php navigation link handler, which failed to reject URLs using the javascript: scheme. A researcher-published writeup exists, but no confirmed active exploitation or CISA KEV listing is present at time of analysis.
RemediationAI
Update Omeka S to a release that incorporates commit 8d47b0ef2dfabc1dd8c52893400321d1fbb5b5f4, which adds javascript: scheme rejection in the navigation URL validator. No specific minimum safe release version is independently confirmed from the available data; administrators should check the Omeka S releases page at https://github.com/omeka/omeka-s to identify the first tagged release containing that commit. As an immediate compensating control, audit all existing site navigation custom URLs for javascript: scheme entries and remove or replace them - this eliminates any planted payloads without requiring a patch. Additionally, restrict site navigation configuration to the smallest set of trusted administrators possible; Omeka S role-based permissions can limit which users may modify site navigation, directly reducing the attack surface. No service disruption is expected from either the patch or the navigation audit.
Affected VersionsENISA
Affects your stack
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Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Omeka S is a PHP-based open-source digital collections and exhibition platform used primarily by cultural institutions and universities. The vulnerability is in application/src/Site/Navigation/Link/Url.php, specifically in the isValid() method responsible for validating custom URL entries in site navigation menus. CWE-79 (Improper Neutralization of Input During Web Page Generation - XSS) applies: the method accepted javascript: scheme URIs as valid navigation targets, which browsers execute as JavaScript when a user clicks the rendered anchor element. The upstream fix (commit 8d47b0ef) adds a parse_url() scheme check that explicitly rejects any URL whose scheme resolves to javascript. This is a well-understood injection class; browsers treat javascript: hrefs as executable code, making any unfiltered acceptance a direct XSS vector. No affected CPE string has been formally registered in NVD at time of publication.
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Severity by source
AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Planting the payload requires site manager or administrator access to navigation configuration, so PR:H is more accurate than the published PR:N.
Primary rating from Vendor (mitre).
CVSS VectorVendor: mitre
Lifecycle Timeline
2DescriptionCVE.org
Cross Site Scripting vulnerability in Omeka S v.4.2.0 allows a remote attacker to execute arbitrary code via the site navigation custom URL function
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
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