CVE-2026-35540 — Incorrect Resource Transfer Between Spheres in Webmail

CWE-669 — Incorrect Resource Transfer Between SpheresCWE-918 — Server-Side Request Forgery9 documents7 sources
Severity
6.5MEDIUMNVD
CNA5.4
EPSS
0.0%
top 86.96%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Roundcube WebmailRoundcube Roundcubemail
Timeline
PublishedApr 3

Description

An issue was discovered in Roundcube Webmail 1.6.0 before 1.6.14. Insufficient Cascading Style Sheets (CSS) sanitization in HTML e-mail messages may lead to SSRF or Information Disclosure, e.g., if stylesheet links point to local network hosts.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:NExploitability: 3.9 | Impact: 2.5

Affected Packages3 packages

▶CVEListV5roundcube/webmail1.6.0 — 1.6.14
▶NVDroundcube/webmail1.6.0 — 1.6.14
▶Packagistroundcube/roundcubemail1.7-beta — 1.7-rc5

Patches

Patch: github.com ↗Patch: github.com ↗

🔴Vulnerability Details

4
OSV
Roundcube Webmail: Insufficient CSS sanitization in HTML e-mail messages↗2026-04-03
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GHSA
Roundcube Webmail: Insufficient CSS sanitization in HTML e-mail messages↗2026-04-03
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OSV
CVE-2026-35540: An issue was discovered in Roundcube Webmail 1↗2026-04-03
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CVEList
CVE-2026-35540: An issue was discovered in Roundcube Webmail 1↗2026-04-03
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📋Vendor Advisories

1
Debian
CVE-2026-35540: roundcube - An issue was discovered in Roundcube Webmail 1.6.0 before 1.6.14. Insufficient C...↗2026
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🕵️Threat Intelligence

1
Wiz
CVE-2026-35540 Impact, Exploitability, and Mitigation Steps | Wiz↗
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💬Community

2
Bugzilla
CVE-2026-35538 CVE-2026-35539 CVE-2026-35540 CVE-2026-35541 CVE-2026-35542 CVE-2026-35544 roundcubemail: various flaws [epel-all]↗2026-04-03
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Bugzilla
CVE-2026-35538 CVE-2026-35539 CVE-2026-35540 CVE-2026-35541 CVE-2026-35542 CVE-2026-35544 roundcubemail: various flaws [fedora-all]↗2026-04-03
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CVE-2026-35540 — Roundcube Webmail vulnerability | cvebase