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CVE-2026-35544

21
FAUCET Score

CVE-2026-35544 describes an insufficient CSS sanitization vulnerability affecting Roundcube Webmail versions prior to 1.5.14 and 1.6.14. This flaw allows a fixed-position mitigation bypass in HTML e-mail messages through the use of "!important" in CSS. Rated with a CVSSv3.1 score of 5.3 (Medium), it has a network attack vector, low attack complexity, and requires no user interaction. The potential impact is limited to low integrity, specifically bypassing a security control, with no direct confidentiality or availability impact. There is currently no evidence of active exploitation, no public exploit code available, and minimal community attention or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.5.13CPE matchmatch criteria
cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*
>= 1.6.0, <= 1.6.13CPE matchmatch criteria
cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*
>= 0, < 1.5.14CPE match
cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*
>= 1.6.0, < 1.6.14CPE match
cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.37%
Probability of exploitation in next 30 days
EPSS Percentile
29.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0037 is in the 18th percentile among its peer group of 23,725 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

composerpatch availablevia ghsa
Product: roundcube/roundcubemailFixed in: 1.7-rc5
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-xpqh-grpw-4xmgmedium

Roundcube Webmail: Insufficient CSS sanitization in HTML e-mail messages

Apr 3, 2026

References

github.com / roundcube/roundcubemail/commit/099009b9c8e1d3c636fb9a5af72f7c2596018662
Patch
github.com / roundcube/roundcubemail/commit/226811a1c974271dbedca72672923abaff8191c0
Patch
github.com / roundcube/roundcubemail/commit/57dec0c127b98e0c8e3b9c26c80049b9c4bcaea7
Patch
github.com / roundcube/roundcubemail/releases/tag/1.5.14
Release Notes
github.com / roundcube/roundcubemail/releases/tag/1.6.14
Release Notes
github.com / roundcube/roundcubemail/releases/tag/1.7-rc5
Release Notes
roundcube.net / news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14
Vendor Advisory