CVE-2026-73374

Stored Cross-Site Scripting (XSS) via Unescaped CNA Reference Tags in vulnerability-lookup

Published Aug 12, 2026 CVSS 4.0 · 6.1 Medium EPSS < 1% KEV · Not listed
Description
A stored cross-site scripting (XSS) vulnerability existed in Vulnerability-Lookup in the render_tag_badges Jinja filter used to display reference tags associated with vulnerability records.

Values from containers.cna.references[].tags[] were directly interpolated into HTML badge elements and the resulting string was wrapped in markupsafe.Markup. Because Markup marks the generated content as safe, Jinja's automatic HTML escaping was bypassed.

An authenticated user with permissions to create or modify vulnerability records, such as a user holding the vulnerability:create or vulnerability:modify permission, could submit a crafted reference tag through the CNA API containing arbitrary HTML or JavaScript-capable markup.

The malicious value would subsequently be stored as part of the vulnerability record. When another user visited the corresponding public /cve/<id> or /vuln/<id> page, the crafted tag would be rendered as HTML in the viewer's browser. This could result in JavaScript execution in the security context of the Vulnerability-Lookup application.

Successful exploitation could allow an attacker to perform actions in the context of a victim, access information available to the victim's browser session, or modify page content. As the affected vulnerability pages can be accessed publicly, exploitation may affect users who are not authenticated.

The issue was corrected by applying markupsafe.escape() to each reference tag before inserting it into the HTML badge markup, while retaining Markup only for the static HTML scaffolding.

Remediation

No solution or workaround provided in the CVE record

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Circl
Circl vulnerability-lookup
Vendors & Products Circl
Circl vulnerability-lookup
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A stored cross-site scripting (XSS) vulnerability existed in Vulnerability-Lookup in the render_tag_badges Jinja filter used to display reference tags associated with vulnerability records. Values from containers.cna.references[].tags[] were directly interpolated into HTML badge elements and the resulting string was wrapped in markupsafe.Markup. Because Markup marks the generated content as safe, Jinja's automatic HTML escaping was bypassed. An authenticated user with permissions to create or modify vulnerability records, such as a user holding the vulnerability:create or vulnerability:modify permission, could submit a crafted reference tag through the CNA API containing arbitrary HTML or JavaScript-capable markup. The malicious value would subsequently be stored as part of the vulnerability record. When another user visited the corresponding public /cve/<id> or /vuln/<id> page, the crafted tag would be rendered as HTML in the viewer's browser. This could result in JavaScript execution in the security context of the Vulnerability-Lookup application. Successful exploitation could allow an attacker to perform actions in the context of a victim, access information available to the victim's browser session, or modify page content. As the affected vulnerability pages can be accessed publicly, exploitation may affect users who are not authenticated. The issue was corrected by applying markupsafe.escape() to each reference tag before inserting it into the HTML badge markup, while retaining Markup only for the static HTML scaffolding.
Title Stored Cross-Site Scripting (XSS) via Unescaped CNA Reference Tags in vulnerability-lookup
Weaknesses CWE-79
References
Metrics cvssV4_0

{'score': 6.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:H/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
CIRCL
Published
Updated
Aug 12, 2026, 5:12 PM
Reserved
Aug 12, 2026, 2:05 PM
Status
Deferred
Published
Aug 12, 2026, 3:18 PM
Modified
Aug 26, 2026, 4:49 PM