Horde
CVE-2021-26929
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
An XSS issue was discovered in Horde Groupware Webmail Edition through 5.2.22 (where the Horde_Text_Filter library before 2.3.7 is used). Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. 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. An XSS issue was discovered in Horde Groupware Webmail Edition through 5.2.22 (where the Horde_Text_Filter library before 2.3.7 is used). The attacker can send a plain text e-mail message, with JavaScript encoded as a link or email that is mishandled by preProcess in Text2html.php, because bespoke use of \x00\x00\x00 and \x01\x01\x01 interferes with XSS defenses. Affected products include: Horde Groupware, Debian Debian Linux. Version information: through 5.2.22.
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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
An XSS issue was discovered in Horde Groupware Webmail Edition through 5.2.22 (where the Horde_Text_Filter library before 2.3.7 is used). The attacker can send a plain text e-mail message, with JavaScript encoded as a link or email that is mishandled by preProcess in Text2html.php, because bespoke use of \x00\x00\x00 and \x01\x01\x01 interferes with XSS defenses.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Exploit-DB
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
The framework/Util/lib/Horde/Variables.php script in the Util library in Horde before 5.1.1 allows remote attackers to c
Horde 3.3.12, Horde Groupware 1.2.10, and Horde Groupware Webmail Edition 1.2.10, as distributed by FTP between November
Horde Groupware Webmail Edition 5.2.22 allows injection of arbitrary PHP code via CSV data, leading to remote code execu
Remote code execution was discovered in Horde Groupware Webmail 5.2.22 and 5.2.17. Rated high severity (CVSS 8.8), this
The File Manager (gollem) module 3.0.11 in Horde Groupware 5.2.21 allows remote attackers to bypass Horde authentication
Horde Trean, as used in Horde Groupware Webmail Edition through 5.2.22 and other products, allows CSRF, as demonstrated
A Remote Code Execution vulnerability has been found in the Horde_Image library when using the "Im" backend that utilize
Horde Groupware Webmail Edition through 5.2.22 allows a reflection injection attack through which an attacker can instan
In Horde_Crypt before 2.7.6, as used in Horde Groupware Webmail Edition through 5.2.17, OS Command Injection can occur i
Multiple cross-site request forgery (CSRF) vulnerabilities in Horde before 5.2.8, Horde Groupware before 5.2.11, and Hor
This vulnerability allows remote attackers to create arbitrary files on affected installations of Horde Groupware Webmai
This vulnerability allows remote attackers to execute local PHP files on affected installations of Horde Groupware Webma