Cyber Resilience

CVE-2026-23794

XSS in Apache Syncope 3.0.0 – 3.0.16

XSS
Published
03 February 2026
Modified
06 February 2026
CVSS Score v3.1 6.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N
EPSS Score 0.0036 29th percentile
Risk Priority 36 floored blend · peak EPSS

Summary

CVE-2026-23794 is a medium-severity Cross-site Scripting (CWE-79) vulnerability in Apache Syncope. Its CVSS base score is 6.8 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Web Portal Capture (T1056.003); ranked at the 29th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SI-15 (Information Output Filtering) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

Reflected XSS in Apache Syncope's Enduser Login page. An attacker that tricks a legitimate user into clicking a malicious link and logging in to Syncope Enduser could steal that user's credentials. This issue affects Apache Syncope: from 3.0 through 3.0.15,…

more

from 4.0 through 4.0.3. Users are recommended to upgrade to version 3.0.16 / 4.0.4, which fix this issue.

CWE(s)
CWE-79

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1056.003 Web Portal Capture Collection
Adversaries may install code on externally facing portals, such as a VPN login page, to capture and transmit credentials of users who attempt to log into the service.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

Reflected XSS on public login page directly enables web portal credential capture (T1056.003) when victim follows attacker link; also constitutes exploitation of public-facing web application (T1190).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2023-28158Same vendor: Apache
CVE-2023-47265Same vendor: Apache
CVE-2023-43701Same vendor: Apache
CVE-2023-22849Same vendor: Apache
CVE-2023-45757Same vendor: Apache
CVE-2023-29247Same vendor: Apache
CVE-2023-37581Same vendor: Apache
CVE-2023-38435Same vendor: Apache
CVE-2023-49145Same vendor: Apache
CVE-2023-5564Shared CWE-79

Affected Assets

apache
syncope
3.0.0 — 3.0.16 · 4.0.0 — 4.0.4

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SI-10 Information Input Validation
  • SI-15 Information Output Filtering
  • AC-4 Information Flow Enforcement
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.1.2
  • V1.3.2

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match
prevent

Directly requires validation of untrusted input to the Enduser login page, blocking the malicious script payload that enables reflected XSS.

SI-15 Information Output Filtering good match
prevent

Requires filtering or encoding of data returned in HTTP responses, neutralizing reflected script content before it executes in the victim's browser.

AC-4 Information Flow Enforcement partial match
prevent

Enforces information flow rules that can block untrusted data containing scripts from being reflected back to authenticated users.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly target introduction of XSS via coding standards/testing (mostly), yet the single broad outcome leaves many specific neutralization vectors unaddressed (partial).

PR.PS-02 partial match
prevents

Patching and EOL replacement can remediate known XSS instances in libraries or frameworks (partial) but do nothing to enforce input neutralization in application code (none).

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
detects

Secure-coding testing and automated code-analysis tools are applied to detect improper neutralization of script-related content during web-page generation.

A.5.6 Contact with special interest groups partial match
prevents

Knowledge exchange on emerging attack techniques and patches reduces the likelihood that cross-site scripting flaws remain unaddressed in deployed applications.

A.5.7 Threat intelligence partial match
prevents

Operational indicators of compromise for web-application attacks can be incorporated into WAF or input-filtering rules, lowering the likelihood that unsanitized data reaches the browser.

A.8.25 Secure development life cycle partial match
prevents

Requiring language-specific secure-coding standards and automated scanning during the SDLC catches missing output encoding or improper neutralization of untrusted data before the software reaches production.

A.8.28 Secure coding partial match
prevents

Secure-coding standards, SAST scans and removal of insecure code samples together eliminate the failure to neutralize script content that produces cross-site scripting flaws.

A.8.7 Protection against malware none match
none

Webpage malware scanning and block-listing of known malicious sites reduce the likelihood that reflected or stored script payloads reach a user’s browser.

References