Bug 2558746 (CVE-2026-114731)

Summary: CVE-2026-114731 roundcubemail: roundcubemail: Denial of Service via CSS proxy memory exhaustion
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Roundcube Webmail. This flaw allows a remote attacker to trigger a Denial of Service (DoS) by exhausting server memory. The application's stylesheet proxy fails to enforce size limits or read timeouts when retrieving external content. By directing the proxy to fetch an attacker-controlled stylesheet, an attacker can force the server to load unbounded data into memory, causing the application to become unresponsive.
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Description OSIDB Bzimport 2026-10-22 02:42:53 UTC 
Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by an uncontrolled resource consumption vulnerability in the CSS proxy (the utils/modcss action). The fetched stylesheet was read into memory in full, with no size limit and no read timeout, so a stylesheet URL referencing an attacker-controlled host could be used to exhaust server memory. Upstream fixed this in the commit “Add a size limit to the CSS proxy content processing”, which caps the response at 5 MB, reads it as a stream and applies a read timeout.