CVE-2026-111269 libical CVE debrief

Who should care

Defenders and security teams responsible for systems using libical versions up to 4.0.6 should assess exposure and prioritize remediation. This includes reviewing and applying patches or updates provided by the vendor, monitoring for potential exploitation attempts, and verifying inventory and configurations for affected versions. Security teams should also implement compensating controls for exposed systems while remediation is scheduled and verified, and

Why it matters

CVE-2026-111269 is a medium-severity vulnerability in libical through 4.0.6, allowing for heap-based out-of-bounds reads. Defenders should assess exposure, prioritize remediation, and monitor for potential exploitation attempts.

• Potential application crashes or denial of service
• Possible information disclosure through heap memory leaks
• Requires verification of affected versions and exposure
• Remediation priority for systems using libical versions up to 4.0.6

Technical summary

libical through 4.0.6 contains a heap-based out-of-bounds read in icalvalue_decode_ical_string() in src/libical/icalvalue.c when decoding input ending in a backslash. Attackers can supply escaped iCalendar text with a trailing backslash, causing the loop to read past the terminator and crash the application or leak adjacent heap memory. The issue is triggered by a specific sequence of input that is not properly handled, leading to potential application crashes or information disclosure through heap memory leaks. Defenders should assess exposure and prioritize remediation for systems using libical versions up to 4.0.6.

Defensive priority

Medium

Recommended defensive actions

• Assess exposure and prioritize remediation for systems using libical versions up to 4.0.6
• Review and apply patches or updates provided by the vendor
• Monitor for potential exploitation attempts
• Verify inventory and configurations for affected versions
• Implement compensating controls for exposed systems while remediation is scheduled and verified
• Review 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 CVE record and source item provide details on a heap-based out-of-bounds read in icalvalue_decode_ical_string() in src/libical/icalvalue.c. The issue is triggered by decoding input ending in a backslash. Attackers can supply escaped iCalendar text with a trailing backslash, causing the loop to read past the terminator and crash the application or leak adjacent heap 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.