CVE-2026-35545: Roundcube Webmail remote image blocking bypass in SVG content

CVE-2026-35545 · Severity: medium · CVSS 5.3 · Published 2026-04-03

Roundcube Webmail, a widely used open-source email client, is vulnerable to a security bypass that allows remote images to load even when the user has blocked them. By sending a specially crafted email containing specific SVG image elements, an attacker can track when a user opens an email or potentially bypass certain access controls. This can lead to unauthorized information disclosure, such as confirming a user's IP address and active status to a malicious sender.

Technologies: roundcube/roundcubemail (Packagist), Roundcube Webmail. Vendors: Packagist, Roundcube.

Quick answers

Is CVE-2026-35545 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-35545 being exploited in the wild.
How severe is CVE-2026-35545?
Medium severity, with a CVSS score of 5.3, published 3 April 2026.
Which products and versions are affected?
roundcube/roundcubemail (Packagist) ECOSYSTEM:introduced=1.7-beta,fixed=1.7-rc5; Roundcube Webmail < 1.5.15, 1.6.0 < 1.6.15, 1.7-rc < 1.7-rc6.
Is there a fix for CVE-2026-35545?
Yes. roundcube/roundcubemail (Packagist): upgrade to 1.7-rc5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-35545 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-35545?
Check whether you run roundcube/roundcubemail (Packagist) or Roundcube Webmail at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • roundcube/roundcubemail (Packagist): upgrade to 1.7-rc5 or later
    composer require roundcube/roundcubemail:^1.7-rc5

Technical details

A vulnerability exists in Roundcube Webmail's HTML sanitization engine (rcube_washtml.php) where the remote image blocking feature can be bypassed. The flaw involves the 'animate' element within SVG content using 'fill', 'filter', or 'stroke' attributes. By utilizing Functional Internal Reference Identifiers (FUNCIRI) within these attributes, an attacker can force the webmail client to load external resources without user consent. This bypass allows for unauthorized remote image loading, which can be used for tracking or information disclosure. Patches have been released in versions 1.5.15, 1.6.15, and 1.7-rc6.

Affected products

  • Roundcube Webmail < 1.5.15, 1.6.0 < 1.6.15, 1.7-rc < 1.7-rc6

Identifiers

  • CVE-2026-35545
  • GHSA-w846-74jr-76cv

Timeline

  • 2026-03-29: patched: Security updates 1.5.15, 1.6.15, and 1.7-rc6 released
  • 2026-04-03: disclosed: CVE-2026-35545 published

References

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