CVE-2026-113386
Description
A flaw was found in Roundcube Webmail. A remote authenticated attacker can exploit this vulnerability by injecting Carriage Return and Line Feed (CRLF) sequences into the _uid parameter during message header or source viewing requests. This flaw enables the attacker to execute arbitrary Internet Message Access Protocol (IMAP) commands on the connected mail server, potentially allowing unauthorized access to or manipulation of email data.
Statement
Red Hat Product Security has determined that this vulnerability does not affect any currently supported Red Hat product. This assessment may evolve based on further analysis and discovery. For more information about this vulnerability and the products it affects, please see the linked references.
Mitigation
--- CME Mitigation Guidance (2026-10-20) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to reject or sanitize carriage return and line feed sequences in the _uid parameter before passing them to backend IMAP commands: upgrade to roundcubemail 1.6.20 and 1.7.5 (or the fixed Roundcubemail builds), which reject or abort processing when the _uid parameter matches the [\r\n] regular expression, closing all 2 injection vectors (CRLF injection via the _uid parameter in mail/headers, CRLF injection via the _uid parameter in mail/viewsource). Until patched, this is a concern on Roundcube Webmail deployments with authenticated user access across any platform, so Restrict network access to authenticated Roundcube sessions and monitor or filter requests to the mail/headers and mail/viewsource actions for newline characters. As a compensating measure, Restrict the _uid parameter to an allowlist of permitted characters such as numeric message UIDs, rejecting all control characters by default. These controls limit blast radius and contain exploitation, but they do not fix the underlying CRLF injection defect — apply the upstream patch to fully remediate.
Highest-impact CME: CME-1313 CRLF / Line Injection Prevention (Newline Sanitization for Structured Formats) (high)
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