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CVE-2021-26929

30
FAUCET Score

CVE-2021-26929 is a medium-severity cross-site scripting (XSS) vulnerability affecting Horde Groupware Webmail Edition through version 5.2.22, specifically when using the Horde_Text_Filter library before 2.3.7. An attacker can exploit this by sending a specially crafted plain text email containing JavaScript, which is improperly handled by the Text2html.php component due to flawed XSS defenses. The vulnerability has a CVSS score of 6.1, indicating it can be exploited over the network with low attack complexity, requiring user interaction, and potentially leading to low confidentiality and integrity impacts. While there is no evidence of active exploitation or Metasploit/Nuclei modules, a public exploit (EDB-49769) exists, though community discussion and media coverage are minimal.

Impacted Technologies

VendorProductVersion(s)CPE
<= 5.2.22CPE matchmatch criteria
cpe:2.3:a:horde:groupware:*:*:*:*:webmail:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.1MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
4.94%
Probability of exploitation in next 30 days
EPSS Percentile
91.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
ExploitDB: EDB-49769 · Apr 15, 2021
This CVE's current EPSS score of 0.0494 is in the 96th percentile among its peer group of 26,234 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

packetstormsecurity.com / files/162187/Webmail-Edition-5.2.22-XSS-Remote-Code-Execution.html
ExploitThird Party AdvisoryVDB Entry
packetstormsecurity.com / files/162194/Horde-Groupware-Webmail-5.2.22-Cross-Site-Scripting.html
Third Party Advisory
github.com / horde/webmail/releases
Third Party Advisory
lists.debian.org / debian-lts-announce/2021/02/msg00028.html
Mailing ListThird Party Advisory
lists.horde.org / archives/announce/2021/001298.html
Mailing ListVendor Advisory
alexbirnberg.com / horde-xss.html
ExploitThird Party Advisory
horde.org / apps/webmail
Vendor Advisory