CVE-2026-114723 Roundcube CVE debrief

Who should care

Defenders responsible for Roundcube Webmail instances should assess exposure and prioritize patching vulnerable versions to prevent potential memory exhaustion attacks. This includes operators, platform administrators, vulnerability management teams, and security teams who need to verify affected versions, apply patches, and monitor server memory usage to detect potential attacks.

Why it matters

CVE-2026-114723 is a vulnerability in Roundcube Webmail that allows ImageMagick resource limits to be bypassed during thumbnail generation, potentially leading to server memory exhaustion. Defenders should prioritize patching vulnerable instances to prevent potential attacks.

• Memory exhaustion attacks may occur if vulnerable instances are exposed to crafted images
• Defenders must verify affected versions and apply patches to prevent exploitation
• Monitoring server memory usage is necessary to detect potential attacks

Technical summary

The vulnerability allows the ImageMagick resource limits to be bypassed during thumbnail generation, potentially leading to server memory exhaustion. The vulnerability affects Roundcube Webmail versions before 1.6.20 and 1.7.x before 1.7.5. This occurs when rcube_image falls back to GD and the available-memory check is not applied on non-Windows platforms, allowing crafted images with large dimensions to be processed without resource limits, potentially exhausting server memory. Defenders should prioritize patching vulnerable Roundcube Webmail instances to prevent potential memory exhaustion attacks. Upstream fixed this in the commit 'Fix ImageMagick resource limits bypass by GD fallback during thumbnail',apply

Defensive priority

Defenders should prioritize patching vulnerable Roundcube Webmail instances to prevent potential memory exhaustion attacks.

Recommended defensive actions

• Patch vulnerable Roundcube Webmail instances to version 1.6.20 or 1.7.5
• Restrict image uploads to trusted sources
• Monitor server memory usage for unusual activity
• Verify affected versions and apply patches to prevent exploitation
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The vulnerability is caused by the ImageMagick resource limits being bypassed during thumbnail generation. When rcube_image falls back to GD, the available-memory check was applied only on Windows, so on other platforms a crafted image with large dimensions was processed by GD without any resource limit and could exhaust server memory.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.