6.1

CVE-2021-26929: debian debian_linux Cross-site Scripting

CVSS: 6.1v3.1MediumModified
AliasesUBUNTU-CVE-2021-26929DEBIAN-CVE-2021-26929DLA-2564-1
Published 14-02-2021Last modified 03-08-2024
Open JSON

Vulnerability summary

CVE-2021-26929 is a medium (CVSS 6.1) Cross-site Scripting vulnerability in debian debian_linux. EPSS estimates a 4.94% chance of exploitation in the next 30 days, higher than 92% of scored vulnerabilities. 3 public exploits are recorded.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.1/10
010
Medium · v3.1 (NVD)
EPSS score
4.94%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits3reference, exploit-database

Timeline

  1. 14-02-2021
    PublishedVulnerability first disclosed.
  2. 03-08-2024
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

4.94%

Chance of exploitation in the next 30 days

Percentile

92%

Versus all other CVEs

30-day change

0.00 pp

From 4.94% on 19-09-2026

19-09-202619-10-2026
EPSS score
4.94%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

3 found
  • referenceUnverified

    Exploit Reference (alexbirnberg.com)

    Maturity: unknown

  • referenceUnverified

    Exploit Reference (packetstormsecurity.com)

    Maturity: unknown

  • exploit-databasemultipleUnverified

    Horde Groupware Webmail 5.2.22 - Stored XSS

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Debian2 products
  • php-horde-text-filter< 2.3.7-1 | < 2.3.5-1+deb9u1
  • debian_linuxEOL9.0
Horde1 product
Ubuntu1 product
  • php-horde-text-filterAll versions (No fix recorded)

3 vendors · 4 products

References

12 links
Show all 12 references