CVE-2023-0835Public exploitNetwork attack vector

Local file disclosure via unsanitized Markdown scripts

Published Apr 4, 2023 · Updated Dec 3, 2025

Cross-site scripting in Alan Shaw Markdown PDF 11.0.0 and earlier allows remote attackers to read arbitrary local files via crafted Markdown. The conversion pipeline turns attacker-controlled Markdown into HTML without neutralizing script elements, allowing JavaScript to issue a file-scheme XMLHttpRequest and embed the response in the generated PDF. Exploitation requires malicious Markdown to reach a converter invocation; the demonstrated payload reads /etc/passwd, and the resulting PDF exposes the file contents.

CVSS severity7.5
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Alan Shaw Markdown PDF 11.0.0 and earlier allows remote attackers to read arbitrary local files via crafted Markdown. The conversion pipeline turns attacker-controlled Markdown into HTML without neutralizing script elements, allowing JavaScript to issue a file-scheme XMLHttpRequest and embed the response in the generated PDF. Exploitation requires malicious Markdown to reach a converter invocation; the demonstrated payload reads /etc/passwd, and the resulting PDF exposes the file contents.

The record

CVE
CVE-2023-0835
Published
Apr 4, 2023
Updated
Dec 3, 2025
Vendor
Alan Shaw
Product
Markdown PDF
Classifications
CWE-79, T1005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 3, 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=11.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Alan Shaw · Markdown PDFversion=11.0.0

Published CVSS scores

7.5Fluid AttacksCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
8.2CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
8.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1005Data from Local System

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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