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Apache Sling XSS CVE-2026-73192

| EUVDEUVD-2026-85173 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-09-23 apache GHSA-84wv-6469-cpqp
6.1
CVSS 3.1 · Vendor: apache
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Craft malicious href bypassing getValidHref()
  2. Delivery
    Deliver crafted link to victim
  3. Exploit
    Victim clicks and app reflects value
  4. Execution
    Sanitizer fails to neutralize payload
  5. Impact
    Script executes in victim browser session

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 a downstream application that uses XSSAPI.getValidHref() from Apache Sling XSS 2.4.10 or earlier as its sanitizer for attacker-influenced href/link values AND reflects that value back into a rendered web page. The attacker must be able to submit a value that this method fails to neutralize, and a victim must interact (click a crafted link) for the reflected script to fire. Limiting factors: the flaw is only reachable if getValidHref() is the effective sanitization control on that data path, victim user interaction is needed, and impact is confined to the victim's browser session rather than the server.

Impact

This is a genuinely low-priority issue despite the XSS classification. No CVSS score, EPSS probability, KEV listing, or public POC is provided in any of the intelligence sources, so there is no evidence of active exploitation or automated weaponization - exploitation status is 'no public exploit identified at time of analysis'. The affected component is Apache Sling XSS, a defensive Java sanitization library rather than a directly network-exposed service; the flaw is that XSSAPI.getValidHref() fails to fully sanitize certain attacker-supplied values, meaning the vulnerability only manifests in downstream applications (notably Adobe AEM/Sling deployments) that rely on this method as their sole href sanitizer AND that reflect the value back to a victim. It is a reflected XSS requiring victim interaction, yielding limited confidentiality/integrity impact in the victim's browser session. No CVSS vector is supplied by the vendor, so authentication requirements cannot be confirmed from the input data; based on the description, exploitation is remote against an application that echoes the tainted value. Net: this is a real-but-narrow library hardening fix, not an urgent widespread threat.

Exploit ScenarioDerived

An attacker crafts a URL containing a malicious href value that survives XSSAPI.getValidHref() sanitization and lures a victim to click it (e.g. against an AEM/Sling application feature that uses this method to validate links). When the victim's browser renders the reflected, improperly-neutralized value, attacker-controlled script executes in the victim's session context. No public exploit code is identified at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 23, 2026

Reflected cross-site scripting in the Apache Sling XSS library 2.4.10 and earlier arises because the XSSAPI.getValidHref() helper fails to properly neutralize certain attacker-supplied values, returning an href that a consuming application may then render into a page. Remote, unauthenticated attackers can exploit this only where a downstream application actually uses getValidHref() as its sanitizer for attacker-influenced link values and reflects that value back to users, and a victim must click a crafted link for the script to execute (assessed CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N). No public exploit code and no confirmed active exploitation were identified at time of analysis, and overall risk is low because reachability depends entirely on how an embedding application wires up this method.

RemediationAI

Vendor-released patch: upgrade Apache Sling XSS to version 2.4.12 or later (from the affected 2.4.10 and prior range), a library-level dependency update that must be propagated by every consuming application - see the Apache Sling news/advisory page at https://sling.apache.org/news.html for release details. If the upgrade cannot be applied immediately, the most effective compensating control is to stop trusting XSSAPI.getValidHref() as the sole sanitizer on attacker-influenced data paths: validate href values server-side against a strict scheme allowlist (for example http, https, mailto, and application-relative paths, rejecting javascript:, data:, and vbscript:) and then apply contextual HTML attribute output encoding at the point of rendering. The trade-off is that this responsibility shifts to every call site and is easy to miss or implement inconsistently, so it should be treated as temporary. A restrictive Content-Security-Policy with a script-src allowlist reduces the chance that a reflected payload executes but is only defense-in-depth, may break legitimate inline scripts, and does not fix the underlying sanitization gap. Note that no GITHUB commit or PR-based fix is referenced in the available intelligence; the remediation path is the tagged library release.

Affected VersionsENISA

Apache Sling XSS 0 <2.4.12

Affected Packages

euvd apache_sling_xss fix: 2.4.12

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Apache Sling XSS is a Java library that provides anti-XSS utilities for Sling-based (and other Java) web applications; XSSAPI.getValidHref() is the specific helper intended to validate/clean values destined for HTML href attributes, typically by rejecting dangerous URI schemes such as javascript:. The defect maps to CWE-79 (Improper Neutralization of Input During Web Page Generation) and is a library-level sanitization failure rather than a flaw in a directly exposed endpoint: the method can return an href string that still permits script execution when embedded in a rendered link, so the vulnerability is inherited by every application whose data path routes attacker-influenced link values through this call. The CPE entry cpe:2.3:a:apache_software_foundation:apache_sling_xss:*:*:*:*:*:*:*:* reflects that the affected component is the library itself, with versions 2.4.10 and prior impacted and 2.4.12 carrying the fix. The assessed vector's S:C scope change and low C:L/I:L ratings are consistent with injected script executing in the victim's browser context, affecting that session rather than server-side data or availability (A:N); the PR:N/UI:R components confirm unauthenticated triggering that nonetheless requires victim interaction.

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Severity by source

Vendor (apache) PRIMARY 6.1 LOW
AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
vuln.today AI 6.1 MEDIUM

Standard reflected XSS: network vector, victim click (UI:R), scope change into browser (S:C), limited confidentiality/integrity of the victim session, no availability impact.

3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (apache).

CVSS VectorVendor: apache

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

Lifecycle Timeline

1
Patch available
Sep 23, 2026 - 11:17 EUVD

DescriptionCVE.org

An improper neutralization of input during web page generation ('Cross-site Scripting') [CWE-79] vulnerability when using the XSSAPI.getValidHref() in Apache Sling XSS version 2.4.10 and prior may allow an attacker to perform a reflected cross-site scripting (XSS) attack in every feature using this method. In order to successfully attack an application, the attacker needs to be able to submit a value which is not correctly sanitized by that library.

Upgrade to Apache Sling XSS >= 2.4.12

Threat Intelligence Overview

EPSS Score
0.2%
Top 89% exploitable
Prevalence
Low
niche Java XSS-protection library used mainly in Adobe AEM/Sling stacks
Data Quality
6 sources
Confidence: High

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.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

30
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +30
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

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