# CVE-2026-35538: Roundcube Webmail IMAP injection in mail search

Source: https://junglewise.ai/threats/cve-2026-35538-roundcube-webmail-imap-injection-in-mail-search  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-03. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-35538 · Severity: low · CVSS 3.1 · Published 2026-04-03

Roundcube Webmail, a popular open-source web-based email client, contains a security flaw in its mail search functionality. An attacker could exploit this to bypass security protections (CSRF) or manipulate email server commands. This could allow an unauthorized user to perform actions on behalf of a legitimate user or interfere with mail processing operations.

Technologies: [roundcube/roundcubemail (Packagist)](https://junglewise.ai/threats/technologies/roundcube-roundcubemail), [Roundcube Webmail](https://junglewise.ai/threats/technologies/webmail). Vendors: [Packagist](https://junglewise.ai/threats/vendors/packagist), [Roundcube](https://junglewise.ai/threats/vendors/roundcube).

## Quick answers

**Is CVE-2026-35538 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-35538 being exploited in the wild.

**How severe is CVE-2026-35538?** Low severity, with a CVSS score of 3.1, published 3 April 2026.

**Which products and versions are affected?** roundcube/roundcubemail (Packagist) ECOSYSTEM:introduced=1.7-beta,fixed=1.7-rc5; Roundcube Webmail < 1.5.14, 1.6.x < 1.6.14, 1.7-rc < 1.7-rc5.

**Is there a fix for CVE-2026-35538?** 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-2026-35538 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-35538?** 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

  ```sh
  composer require roundcube/roundcubemail:^1.7-rc5
  ```


## Technical details

A vulnerability exists in Roundcube Webmail's mail search component (program/actions/mail/search.php) due to improper neutralization of argument delimiters (CWE-88). Specifically, unsanitized IMAP SEARCH command arguments allow for IMAP injection. This flaw can also be leveraged to achieve a CSRF bypass during mail search operations. The attack requires network access and low-level authentication (PR:L), with a high complexity (AC:H) for successful exploitation. The issue is resolved in versions 1.5.14, 1.6.14, and 1.7-rc5.

## Affected products

- Roundcube Webmail < 1.5.14, 1.6.x < 1.6.14, 1.7-rc < 1.7-rc5

## Identifiers

- CVE-2026-35538
- GHSA-8jr8-v43g-5c57

## Timeline

- 2026-03-18: patched: Security updates released for 1.5, 1.6, and 1.7 branches.
- 2026-04-03: disclosed: CVE-2026-35538 published.

## References

- [https://github.com/roundcube/roundcubemail/commit/5fe8a69956a9683a4269f3ad2a68e18deebf8a15](https://github.com/roundcube/roundcubemail/commit/5fe8a69956a9683a4269f3ad2a68e18deebf8a15)
- [https://github.com/roundcube/roundcubemail/commit/7daf5aa9c190ccc75bb31672d8fee9938877fd64](https://github.com/roundcube/roundcubemail/commit/7daf5aa9c190ccc75bb31672d8fee9938877fd64)
- [https://github.com/roundcube/roundcubemail/commit/b18a8fa8e81571914c0ff55d4e20edb459c6952c](https://github.com/roundcube/roundcubemail/commit/b18a8fa8e81571914c0ff55d4e20edb459c6952c)
- [https://github.com/roundcube/roundcubemail/releases/tag/1.5.14](https://github.com/roundcube/roundcubemail/releases/tag/1.5.14)
- [https://github.com/roundcube/roundcubemail/releases/tag/1.6.14](https://github.com/roundcube/roundcubemail/releases/tag/1.6.14)
- [https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5](https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5)
- [https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14](https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14)

## 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 uncontrolled resource consumption in CSS proxy](https://junglewise.ai/threats/cve-2026-114731-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)