Webmail: Incorrect Resource Transfer Between Spheres
CVE-2026-35545 is a high-severity incorrect resource transfer between spheres vulnerability in Webmail from Roundcube, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 1.5.15, 1.6.15 as the first without the flaw, so updating Webmail to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.41% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Webmail to 1.5.15 or 1.6.15, whichever matches your release line, or a later version.
- Read the advisory on roundcube.net for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Roundcube | Webmail | before 1.5.15; 1.6.0 up to, but not including, 1.6.15 | 1.5.15, 1.6.15 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- LowLimited modification of data is possible.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.3 | Medium | CNA (mitre.org) |
| CVSS 3.1 | 8.2 | High | NVD |
Official description
An issue was discovered in Roundcube Webmail before 1.5.15 and 1.6.15. The remote image blocking feature can be bypassed via SVG content in an e-mail message. This may lead to information disclosure or access-control bypass. This involves the animate element with attributeName=fill/filter/stroke.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Resource Transfer Between Spheres
The product does not properly transfer a resource/behavior to another sphere, or improperly imports a resource/behavior from another sphere, in a manner that provides unintended control over that resource.
More Incorrect Resource Transfer Between Spheres vulnerabilities (CWE-669)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/roundcube/roundcubemail/commit/7ad62de184368bf42c0f522d1aacc030f5ddcc46
- github.com/roundcube/roundcubemail/commit/9d18d524f3cc211003fc99e2e54eed09a2f3da88
- github.com/roundcube/roundcubemail/commit/fe1320b199d3a2f58351bb699c9ed4316e73221b
- github.com/roundcube/roundcubemail/releases/tag/1.5.15Release Notes
- github.com/roundcube/roundcubemail/releases/tag/1.6.15Release Notes
- github.com/roundcube/roundcubemail/releases/tag/1.7-rc6Release Notes
Other vulnerabilities in Webmail
- 8.1 High severity
- 7.2 High severity
- 8.3 High severity
- 8.1 High severity
- 7.1 High severity
- 8.5 High severity
Recent Incorrect Resource Transfer Between Spheres vulnerabilities
- 8.8 High severity
- 8.2 High severity
- 8.8 High severity
- 9.8 Critical severity
- 7.7 High severity
- 7.7 High severity
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