Is CVE-2026-35544 in the CISA KEV catalog?

No. CVE-2026-35544 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-35544?

CVE-2026-35544 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2026-35544?

CVE-2026-35544 has an EPSS score of 0.37% (28th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-35544?

Upgrade roundcube on debian 11 to 1.4.15+dfsg.1-1+deb11u8 or later.

CVE & CISA-KEV Catalog

CVE-2026-35544

MEDIUM

5.3

CVSS v3

NVD

Description

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.

CWE-669

How to fix

Remediation Available

roundcubeDebian

Fixed in:1.4.15+dfsg.1-1+deb11u8CVE-2026-35544

Fixed in:1.6.5+dfsg-1+deb12u8CVE-2026-35544

Fixed in:1.6.15+dfsg-0+deb13u1CVE-2026-35544

Fixed in:1.6.14+dfsg-1CVE-2026-35544

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.37%probability of exploitation in 30 days

28thpercentile

Low risk: more likely to be exploited than 28% of all known CVEs.

References

Patch3

Vendor Advisory1

roundcube.net

Release Notes3

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Markdown

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HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-09.