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Apache Answer CVE-2026-64944

| EUVDEUVD-2026-104152 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
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Attack ChainAIDerived

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

  1. Access
    Gain access to data import feature
  2. Delivery
    Craft data source with malicious HTML in question body
  3. Exploit
    Import persists raw HTML unsanitized
  4. Execution
    Privileged user views imported question
  5. Persist
    Stored script executes in victim browser
  6. Impact
    Hijack session / act as admin

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 that the attacker can supply or control the contents of a data source consumed by Apache Answer's question importer, since only that import path stores bodies as raw HTML while skipping the standard Markdown-to-HTML sanitization applied to normal user content. The payload fires when any user - notably a privileged user - renders the imported question, so no victim action beyond viewing is needed, but the attacker must first reach the import workflow, which in Apache Answer is an administrative/trusted function rather than a public submission form. Authentication requirements are not confirmed from available data (no CVSS vector provided), but the import-feature dependency materially limits exploitation to actors who can introduce malicious import data. Affects Apache Answer through 2.0.2; fixed in 2.0.3.

Impact

This is a genuinely low-priority issue, consistent with the Apache advisory's 'low' severity rating. Key quantitative signals are absent: no CVSS vector, no EPSS score, no CISA KEV listing, and no public POC are present in the input, so exploitation probability cannot be numerically bounded. The vulnerability is a stored XSS (CWE-79 class) that occurs only through the data importer, which persists imported question bodies as raw HTML while bypassing the normal Markdown-to-HTML sanitization path. The critical limiting factor is that exploitation depends on an attacker being able to supply or control an imported data source - in Apache Answer the import function is an administrative/privileged operation, not a public submission path - which sharply narrows the realistic attacker population versus a typical unauthenticated web XSS. The mitigating weight is that the rendered payload executes in the browsers of all viewers, including privileged users, so a successful injection can escalate toward session/account compromise of administrators. Net: real but low-likelihood, requiring a privileged or trusted import step; not an emergency patch but worth closing on normal cadence. No conflicting signals exist because almost no automated-risk telemetry was provided - the assessment rests on the vendor description alone.

Exploit ScenarioDerived

An attacker able to influence an imported data source embeds malicious HTML (e.g. a <script> or event-handler payload) inside a question body. When the importer ingests it, the raw HTML is stored without sanitization and later rendered to every viewer of that question - including administrators - executing attacker JavaScript in their authenticated browser sessions. No public exploit code was identified at time of analysis, and the attack requires access to the import feature rather than a public posting form.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
No patch listed yet 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 16, 2026

Stored cross-site scripting in Apache Answer through 2.0.2 allows an attacker who can control the contents of a data source consumed by the question importer to persist raw, unsanitized HTML that is later rendered to every viewer of the imported question, including privileged users. The importer bypasses the normal Markdown-to-HTML sanitization path applied to ordinary user content, so the injected markup survives storage and executes in the browser of anyone who opens the affected question - no additional victim interaction beyond viewing is required, but the attacker must first reach the administrative/trusted import workflow. The issue is rated low severity by the vendor and carries an assessed vector of CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N; no public exploit code has been identified at time of analysis and there is no indication of active exploitation. A vendor-released patch is available in Apache Answer 2.0.3.

RemediationAI

Upgrade Apache Answer to version 2.0.3, which is the vendor-released patch and the only complete fix for the unsanitized importer path; this closes the gap where imported question bodies bypass the standard Markdown-to-HTML sanitization. Until the upgrade can be scheduled, restrict access to the question-import workflow to a small, trusted set of administrators and treat all imported data sources as untrusted input, since the vulnerable path is reachable only through that administrative/trusted import function - the trade-off is that legitimate bulk imports will require manual review or a staging step rather than self-service by less-trusted staff. Additional compensating controls include enforcing a strict Content-Security-Policy on the Answer deployment so that inline script injected into stored question bodies cannot execute, and reviewing or purging previously imported question content for embedded HTML; be aware that a restrictive CSP may break legitimate embedded media or custom formatting and therefore requires testing before rollout. Because the stored payload is rendered to privileged users as well, any account with access to imported questions should be considered a potential target, and session/credential exposure should be evaluated if imports from untrusted sources have already occurred. Consult the vendor advisory at https://answer.apache.org and the oss-security advisory at https://seclists.org/oss-sec/2026/q4/198 for the authoritative fix guidance.

Affected VersionsENISA

Apache Answer 0 ≤2.0.2

Affected Packages

euvd apache_answer no fix

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

The root cause is improper neutralization of input during web page generation (cross-site scripting), specifically a stored/persistent variant arising from an inconsistent sanitization path in the Apache Answer Q&A platform. Normally, user-submitted question and answer bodies are processed through a Markdown-to-HTML pipeline that sanitizes the resulting markup before persistence and rendering. The question importer, however, stores imported question bodies verbatim as raw HTML, skipping that sanitization stage entirely. Because the stored content is then rendered into the page for all viewers, attacker-controlled HTML embedded in an imported data source becomes executable script in the context of the Answer instance. The assessed CVSS:3.1 vector AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N reflects a network-reachable, low-complexity attack requiring high privileges, with no user interaction, a scope change (S:C) because script executes in the browsing context of other users, and limited confidentiality and integrity impact (C:L/I:L) with no availability impact. The import feature is an administrative or trusted function rather than a public submission form, which materially limits the set of actors who can introduce malicious import data.

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Severity by source

vuln.today AI 5.5 MEDIUM

Import is a privileged admin function so PR:H; payload stored and auto-rendered to viewers gives UI:N and scope change (S:C) into victim browsers with limited C/I impact, no availability effect.

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

Estimated by vuln.today — no official severity rating has been published for this CVE yet.

Description PRE-NVD

Disclosed via oss-security. NVD scoring and full description are pending.

Threat Intelligence Overview

EPSS Score
0.2%
Top 89% exploitable
Prevalence
Low
niche open-source Q&A platform, limited enterprise production footprint
Data Quality
1 sources
Confidence: Low

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 No
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.

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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