Roundcube Webmail up to 1.5.13/1.6.13 IMAP SEARCH Command Argument argument injection

Summaryinfo

A vulnerability classified as critical was found in Roundcube Webmail up to 1.5.13/1.6.13. Affected is an unknown function of the component IMAP SEARCH Command Argument Handler. The manipulation results in argument injection. This vulnerability was named CVE-2026-35538. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical has been found in Roundcube Webmail up to 1.5.13/1.6.13. Affected is an unknown function of the component IMAP SEARCH Command Argument Handler. The manipulation with an unknown input leads to a argument injection vulnerability. CWE is classifying the issue as CWE-88. The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. Unsanitized IMAP SEARCH command arguments could lead to IMAP injection or CSRF bypass during mail search.

The advisory is shared for download at roundcube.net. This vulnerability is traded as CVE-2026-35538 since 04/03/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1059.

The vulnerability scanner Nessus provides a plugin with the ID 304888 (Linux Distros Unpatched Vulnerability : CVE-2026-35538), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.5.14 or 1.6.14 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 5fe8a69956a9683a4269f3ad2a68e18deebf8a15 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (304888) and CERT Bund (WID-SEC-2026-0789). Once again VulDB remains the best source for vulnerability data.

Affected

• Open Source Roundcube

Productinfo

Type

• Mail Client Software

Vendor

• Roundcube

Name

• Webmail

Version

• 1.5.0
• 1.5.1
• 1.5.2
• 1.5.3
• 1.5.4
• 1.5.5
• 1.5.6
• 1.5.7
• 1.5.8
• 1.5.9
• 1.5.10
• 1.5.11
• 1.5.12
• 1.5.13
• 1.6.0
• 1.6.1
• 1.6.2
• 1.6.3
• 1.6.4
• 1.6.5
• 1.6.6
• 1.6.7
• 1.6.8
• 1.6.9
• 1.6.10
• 1.6.11
• 1.6.12
• 1.6.13

License

• free

CPE 2.3info

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CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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