CVE-2026-35543Network attack vector

Information disclosure via SVG animation sanitization bypass

Published Apr 3, 2026 · Updated Apr 3, 2026

Remote image blocking bypass in Roundcube Webmail before 1.5.14 and 1.6.0 through 1.6.13 allows remote attackers to disclose data via email. The rcube_washtml SVG sanitizer blocks animation of href but fails to reject mask or cursor values containing external url() references. Rendering a crafted message loads those references despite remote-image blocking, exposing request-derived information or bypassing resource access controls.

CVSS severity5.3
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Remote image blocking bypass in Roundcube Webmail before 1.5.14 and 1.6.0 through 1.6.13 allows remote attackers to disclose data via email. The rcube_washtml SVG sanitizer blocks animation of href but fails to reject mask or cursor values containing external url() references. Rendering a crafted message loads those references despite remote-image blocking, exposing request-derived information or bypassing resource access controls.

The record

CVE
CVE-2026-35543
Published
Apr 3, 2026
Updated
Apr 3, 2026
Vendor
Roundcube
Product
Roundcube Webmail
Classifications
CWE-669
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.5.14
  2. Affected versionversion=1.6.0 <1.6.14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Roundcube · Roundcube Webmailversion=0 <1.5.14; version=1.6.0 <1.6.14

Published CVSS scores

5.3MITRECVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-669Incorrect Resource Transfer Between Spheres

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo