CVE-2026-35544

An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. Insufficient Cascading Style Sheets (CSS) sanitization in HTML e-mail messages may lead to a fixed-position mitigation bypass via the use of !important.

Published: 2026-04-03 Last update: 2026-04-09 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-35544 is rated Low Risk (31.4/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.37%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-35544

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.03% 0.37% +0.33%
2 2026-04-03 — 0.03% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-35544

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 1.4 [email protected]

Weakness enumeration for CVE-2026-35544

GitHub Security Advisory for CVE-2026-35544

GHSA-xpqh-grpw-4xmg · Severity: medium · Ecosystem: composer — Roundcube Webmail: Insufficient CSS sanitization in HTML e-mail messages

OS Trackers for CVE-2026-35544

vendor priority summary link
debian not yet assigned CVE-2026-35544 not yet assigned priority: Debian including 1 source packages (roundcube), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-35544
ubuntu medium CVE-2026-35544 medium priority: Ubuntu including 1 source packages (roundcube), 7 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): needs-triage 6, released 1. https://ubuntu.com/security/CVE-2026-35544

Affected software / configurations for CVE-2026-35544

Vendor Product Version Raw CPE
roundcube webmail <= 1.5.13 cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*
roundcube webmail >= 1.6.0, <= 1.6.13 cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*

References for CVE-2026-35544

cvelogic Threat Intelligence