CVE-2026-61908 cyrusimap CVE debrief

Who should care

Defenders responsible for Cyrus IMAP servers, particularly those with authenticated user access, should assess exposure and prioritize verification and remediation. This includes reviewing compensating controls for exposed systems while remediation is scheduled and verified, checking relevant monitoring, detection, and logs for exposed assets that need extra review, and tracking exceptions, retesting remediated assets, and closing the item only after证据 is

Why it matters

CVE-2026-61908 is a low-severity vulnerability in Cyrus IMAP that could allow authenticated users to potentially expose adjacent heap memory. Defenders should prioritize verification and remediation, particularly for servers with authenticated user access.

• Potential exposure of adjacent heap memory
• Verification of Cyrus IMAP version and user access controls
• Monitoring for potential exploitation attempts

Technical summary

The vulnerability is caused by an out-of-bounds index reference in the JMAP email-header blob ID. An authenticated user could attempt to download a crafted JMAP blob ID, potentially exposing adjacent heap memory. This issue has a CVSS score of 3.1 and is considered low severity. The vulnerability affects Cyrus IMAP before version 3.12.4. Defenders should prioritize verifying and upgrading to Cyrus IMAP version 3.12.4 or later, and restrict access to authenticated users. The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions.

Defensive priority

Defenders should prioritize verifying and upgrading to Cyrus IMAP version 3.12.4 or later, and restrict access to authenticated users.

Recommended defensive actions

• Verify and upgrade to Cyrus IMAP version 3.12.4 or later
• Restrict access to authenticated users
• Monitor for potential exploitation attempts
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. The vulnerability is caused by an out-of-bounds index reference in the JMAP email-header blob ID. An authenticated user could attempt to download a crafted JMAP blob ID, potentially exposing adjacent heap memory. The issue has a CVSS score of 3.1 and is considered low severity.

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.