# CVE-2026-114731: Roundcube Webmail uncontrolled resource consumption in CSS proxy

Source: https://junglewise.ai/threats/cve-2026-114731-roundcube-webmail-before-1-6-20-and-1-7-x-before-1-7-5-is  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-22. Updated: 2026-10-22  
License: CC BY 4.0 with a link back

CVE-2026-114731 · Severity: medium · CVSS 5.3 · Published 2026-10-22

Roundcube Webmail is an email client that runs in a web browser. An attacker can force the server to download and store unlimited amounts of data from a malicious CSS stylesheet, exhausting server memory and potentially causing a denial of service. This could render the email service unavailable to legitimate users.

Technologies: [Roundcube Webmail](https://junglewise.ai/threats/technologies/webmail). Vendors: [Roundcube](https://junglewise.ai/threats/vendors/roundcube).

## Quick answers

**Is CVE-2026-114731 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-114731 being exploited in the wild.

**How severe is CVE-2026-114731?** Medium severity, with a CVSS score of 5.3, published 22 October 2026.

**Which products and versions are affected?** Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5.

**Is there a fix for CVE-2026-114731?** Yes: fixed in Roundcube Webmail 1.6.20, 1.7.5. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-114731 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-114731?** Check whether you run 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

- Fixed in Roundcube Webmail 1.6.20, 1.7.5

## Technical details

The vulnerability is an uncontrolled resource consumption flaw in the CSS proxy (utils/modcss action) that reads stylesheet content into memory without size limits or read timeouts. An attacker can supply a URL to a malicious stylesheet hosted on an attacker-controlled server, causing the Roundcube server to consume unbounded memory. The fix implements a 5 MB size cap, streams the response, and applies a read timeout.

## Affected products

- Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5

## Timeline

- 2026-10-22: disclosed
- 2026-10-19: patched

## References

- [https://bugs.debian.org/1151279](https://bugs.debian.org/1151279)
- [https://github.com/roundcube/roundcubemail/commit/2c9f6da692fa37cad2aaf85d5b127b583d22b264](https://github.com/roundcube/roundcubemail/commit/2c9f6da692fa37cad2aaf85d5b127b583d22b264)

## Related threats

- [Roundcube Webmail improper authentication in multi-host installations](https://junglewise.ai/threats/cve-2026-114732-roundcube-webmail-before-1-6-20-and-1-7-x-before-1-7-5-is)
- [Roundcube Webmail server-side request forgery filter bypass](https://junglewise.ai/threats/cve-2026-114730-roundcube-webmail-1-6-14-before-1-6-20-and-1-7-0-before-1-7-5-is)
- [Roundcube Webmail content blocking bypass via SVG SMIL](https://junglewise.ai/threats/cve-2026-114729-roundcube-webmail-before-1-6-20-and-1-7-x-before-1-7-5-is)
- [Roundcube Webmail remote content blocking bypass in CSS FuncIRI handling](https://junglewise.ai/threats/cve-2026-114728-roundcube-webmail-before-1-6-20-and-1-7-x-before-1-7-5-is)
- [Roundcube Webmail unsafe content passed to ImageMagick](https://junglewise.ai/threats/cve-2026-114727-roundcube-webmail-before-1-6-20-and-1-7-x-before-1-7-5-passes)