CVE-2023-1536Public exploitNetwork attack vector

Stored script execution via unsanitized Markdown

Published Mar 21, 2023 · Updated Feb 27, 2025

Stored XSS in Apache Answer before 1.0.7 allows remote authenticated users to execute script in another user's browser via crafted Markdown. Markdown2HTML returned the renderer's HTML directly without sanitizing attacker-controlled elements or attributes before storing and displaying the result. Any account allowed to create Markdown content can store the payload, but execution requires another user to view it; the script can then read or alter data available to that viewer.

CVSS severity7.6
High
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Apache Answer before 1.0.7 allows remote authenticated users to execute script in another user's browser via crafted Markdown. Markdown2HTML returned the renderer's HTML directly without sanitizing attacker-controlled elements or attributes before storing and displaying the result. Any account allowed to create Markdown content can store the payload, but execution requires another user to view it; the script can then read or alter data available to that viewer.

The record

CVE
CVE-2023-1536
Published
Mar 21, 2023
Updated
Feb 27, 2025
Vendor
The Apache Software Foundation
Product
Apache Answer
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 21, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 27, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <1.0.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Apache Software Foundation · Apache Answerversion=unspecified <1.0.7

Published CVSS scores

7.6huntr.dev CNACVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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