CVE-2026-107219 qax-os CVE debrief

Who should care

Defenders responsible for securing systems that use the Excelize library should be aware of this vulnerability and take steps to verify the library version and apply any available patches.

Why it matters

CVE-2026-107219 is a vulnerability in the Excelize library that can lead to CPU consumption attacks. Defenders should prioritize verifying the library version and applying any available patches to prevent potential attacks.

• CPU consumption attacks can lead to denial-of-service conditions
• Verification of Excelize library version and patch application is necessary to prevent potential attacks
• Monitoring system resources for unusual CPU consumption patterns can help detect potential attacks

Technical summary

The Excelize library is vulnerable to an unbounded spinCount in agile decryption, which can lead to CPU consumption attacks. The vulnerability occurs when the library attempts to decrypt an OLE encrypted-workbook header with an attacker-controlled spinCount. This can be triggered when a crafted OLE encrypted-workbook header supplies an excessive spinCount and the file is opened, causing the key-derivation loop to perform unbounded attacker-selected work and consume a CPU core for an attacker-controlled duration. Defenders should prioritize verifying the Excelize library version and applying any available patches to prevent potential CPU consumption attacks.

Defensive priority

Defenders should prioritize verifying the Excelize library version and applying any available patches to prevent potential CPU consumption attacks.

Recommended defensive actions

• Verify the Excelize library version and apply any available patches
• Implement input validation to limit the spinCount value
• Monitor system resources for unusual CPU consumption patterns
• 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 vulnerability is caused by the Excelize library's agile decryption process, which accepts an attacker-controlled spinCount and performs that many password-key derivation iterations before verifier validation. This can lead to unbounded CPU consumption when a crafted OLE encrypted-workbook header supplies an excessive spinCount.

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.