6.1

CVE-2026-35539: roundcube webmail Cross-site Scripting

CVSS: 6.1v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2026-35539DEBIAN-CVE-2026-35539
Published 03-04-2026Last modified 03-04-2026
Open JSON

Vulnerability summary

CVE-2026-35539 is a medium (CVSS 6.1) Cross-site Scripting vulnerability in roundcube webmail. EPSS estimates a 0.35% chance of exploitation in the next 30 days, higher than 27.8% of scored vulnerabilities.

Overall risk
24/100
0100
Low · default modelHow is this calculated?
CVSS score
6.1/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.35%
0%100%
Low · +0.10 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 03-04-2026
    PublishedVulnerability first disclosed.
  2. 03-04-2026
    Last modifiedVulnerability information updated.

Description

An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. XSS exists because of insufficient HTML attachment sanitization in preview mode. A victim must preview a text/html attachment.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.35%

Chance of exploitation in the next 30 days

Percentile

28%

Versus all other CVEs

30-day change

+0.10 pp

From 0.25% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.35%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Debian1 product
  • roundcube< 1.6.5+dfsg-1+deb12u8 | < 1.6.15+dfsg-0+deb13u1 | < 1.6.14+dfsg-1
Roundcube1 product
  • webmail< 1.5.14 | ≥ 1.6.0, < 1.6.14
Ubuntu1 product
  • roundcubeAll versions (No fix recorded)

3 vendors · 3 products

References

10 links