Roundcube Webmail up to 1.6.19/1.7.4 IMAP Command _flag command injection

Summaryinfo

A vulnerability, which was classified as critical, was found in Roundcube Webmail up to 1.6.19/1.7.4. This affects an unknown function of the component IMAP Command Handler. The manipulation of the argument _flag results in command injection. This vulnerability is known as CVE-2026-114720. It is possible to launch the attack remotely. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Roundcube Webmail up to 1.6.19/1.7.4. Affected is some unknown functionality of the component IMAP Command Handler. The manipulation of the argument _flag with an unknown input leads to a command injection vulnerability. CWE is classifying the issue as CWE-77. The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by an IMAP command injection vulnerability. A remote authenticated attacker can exploit this via CRLF sequences injected into the _flag parameter of the mail/mark action to execute arbitrary IMAP commands. Upstream fixed this in the commit “Fix IMAP command injection via CRLF in `_flag` parameter of mail/mark action”, which rejects flags containing control, whitespace and IMAP-special characters.

The advisory is available at bugs.debian.org. This vulnerability is traded as CVE-2026-114720 since 10/22/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1202 by the MITRE ATT&CK project.

Upgrading to version 1.6.20 or 1.7.5 eliminates this vulnerability.

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Productinfo

Type

• Mail Client Software

Vendor

• Roundcube

Name

• Webmail

Version

• 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
• 1.6.14
• 1.6.15
• 1.6.16
• 1.6.17
• 1.6.18
• 1.6.19
• 1.7.0
• 1.7.1
• 1.7.2
• 1.7.3
• 1.7.4

License

• free

CPE 2.3info

• 🔒
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CPE 2.2info

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