Hedgedoc
CVE-2021-21259
MEDIUM
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. |
| Impact | CVSS score of 6.1 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, user interaction required. Public proof-of-concept exploit code is available. |
| Exploit ScenarioDerived | A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability. |
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Alert meAnalysisAI
HedgeDoc is open source software which lets you create real-time collaborative markdown notes. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.
Affects your stack
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Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. HedgeDoc is open source software which lets you create real-time collaborative markdown notes. In HedgeDoc before version 1.7.2, an attacker can inject arbitrary JavaScript into a HedgeDoc note, which is executed when the note is viewed in slide mode. Depending on the configuration of the instance, the attacker may not need authentication to create or edit notes. The problem is patched in HedgeDoc 1.7.2. As a workaround, disallow loading JavaScript from 3rd party sites using the Content-Security-Policy header. Note that this will break some embedded content. Affected products include: Hedgedoc. Version information: version 1.7.2.
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Severity by source
AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
HedgeDoc is open source software which lets you create real-time collaborative markdown notes. In HedgeDoc before version 1.7.2, an attacker can inject arbitrary JavaScript into a HedgeDoc note, which is executed when the note is viewed in slide mode. Depending on the configuration of the instance, the attacker may not need authentication to create or edit notes. The problem is patched in HedgeDoc 1.7.2. As a workaround, disallow loading JavaScript from 3rd party sites using the Content-Security-Policy header. Note that this will break some embedded content.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
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.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.
Affected Products (CPE)NVD
HedgeDoc is a collaborative platform for writing and sharing markdown. Rated high severity (CVSS 8.7), this vulnerabilit
HedgeDoc is software for creating real-time collaborative markdown notes. Rated high severity (CVSS 8.2), this vulnerabi
HedgeDoc is an open source, real-time, collaborative, markdown notes application. Rated medium severity (CVSS 6.5), this
HedgeDoc (formerly known as CodiMD) is an open-source collaborative markdown editor. Rated critical severity (CVSS 10.0)
HedgeDoc (formerly known as CodiMD) is an open-source collaborative markdown editor. Rated medium severity (CVSS 5.8), t
Denial of service in HedgeDoc before 1.11.0 lets a user who can store a note crash the instance by embedding a YAML "ali
HedgeDoc is a collaborative platform for writing and sharing markdown. Rated high severity (CVSS 7.5), this vulnerabilit
Rate-limiting bypass in HedgeDoc prior to 1.11.0 permits unauthenticated remote attackers to circumvent brute-force prot
HedgeDoc's GitHub Gist export feature exposes private and protected note content to attacker-controlled GitHub accounts
HedgeDoc is an open source, real-time, collaborative, markdown notes application. Rated medium severity (CVSS 6.4), this
HedgeDoc is a platform to write and share markdown. Rated medium severity (CVSS 6.1), this vulnerability is remotely exp
HedgeDoc is a platform to write and share markdown. Rated medium severity (CVSS 6.1), this vulnerability is remotely exp
Exploit-DB