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CVE-2026-16889

Stored XSS via Pre-Login Notice Image Upload Serves Attacker HTML from Application Origin

CVSS score

4.8

EPSS probability

—

Risk score

0.5

Published

2 h ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Patch status has not yet been verified

Resmî kaynaklarda yeterli kanıt bulunamadı. Bu sonuç “yama yok” anlamına gelmez.

Impact on My Inventory

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Vulnerability description

DayBreach AI Explanation

Verified against sources

Stored XSS Vulnerability in openEQUELLA

Sources read

1

Source agreement

Tam uyum

Evidence confidence

%55

Short explanation

A stored cross-site scripting (XSS) vulnerability in openEQUELLA allows authenticated or privileged users to serve HTML from the application origin [S0].

Why does it matter?

This security flaw enables attackers to serve malicious HTML files from the openEQUELLA origin, resulting in client-side security risks [S0].

What should be done?

  • Follow vendor advisories [S0]
Chain of evidence and sources2 verified claims

openEQUELLA öncesi 2026.1 sürümlerinde pre-login notice image upload uç noktası dosya türlerini doğrulamamaktadır [S0].

S0 · daybreach-canonical

EDIT_SYSTEM_SETTINGS iznine sahip kullanıcılar text/html olarak sunulan HTML dosyaları yükleyebilir [S0].

S0 · daybreach-canonical
Show the technical text from the sources

In openEQUELLA before 2026.1, the pre-login notice image upload endpoint (PUT /api/preloginnotice/image/{name}) does not validate the type of uploaded files and serves them with a Content-Type derived from the supplied filename. A user holding the EDIT_SYSTEM_SETTINGS permission can upload an HTML file that is then served as text/html from the openEQUELLA origin, resulting in stored cross-site scripting. Unauthenticated exploitation is possible where EDIT_SYSTEM_SETTINGS has been granted to the guest user or everyone.

CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

CWE: CWE-434

This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-16889 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1Apereo FoundationopenEQUELLA View
Total affected vendors: 1|Products: 1

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
4.8CVSS V4_0MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:NCVE CNA
4.8CVSS V40MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/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:XNVD

Patch and Remediation Guide

Solution & Remediation Advisory

Patch status unknown

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Until a patch is confirmed, follow the vendor advisory; do not read an unknown status as “no patch”.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-16889 is associated with the following CWEs:

CWE-434: Common Weakness Enumeration Entry CWE-434

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-16889 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsHigh
User—

Official Sources and Advisories

https://github.com/openequella/openEQUELLA/security/advisories/GHSA-q2xv-rffq-mj5wvendor-advisoryhttps://openequella.github.io/guides/vendor-advisory

CVSS Vector Radar Chart

4.8 / 10
Attack VectorNetworkComplexityLowPrivilegesHighUser Interact.RequiredConfidentialityLowIntegrityNoneAvailabilityNone

Vulnerability Scoring Details

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredHigh privileges
User InteractionP
Confidentiality (Gizlilik)Low
Integrity (Bütünlük)P
Availability (Erişilebilirlik)None

Yama durumu bilinmiyor

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Follow the vendor

AF
Apereo Foundation logo
Apereo Foundation

Weakness Type (CWE & CAPEC)

CWE-434

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CVE-2026-16889 · Stored XSS via Pre-Login Notice Image…