CVE-2026-107215 qax-os CVE debrief

Who should care

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

Why it matters

CVE-2026-107215 is a high-severity vulnerability in the Excelize library that allows for remote denial-of-service (DoS) attacks. Defenders should prioritize verifying the library version and applying patches or workarounds to prevent exploitation.

• Remote denial-of-service (DoS) attacks are possible due to unbounded and negative-sized buffer allocations.
• Defenders should verify the Excelize library version and apply patches or workarounds to prevent exploitation.
• The vulnerability can be exploited by crafting a malicious OLE compound file with a negative or extremely large EncryptionInfo or EncryptedPackage stream size.

Technical summary

The Excelize library is vulnerable to a remote denial-of-service (DoS) attack due to unbounded and negative-sized buffer allocations. The vulnerability exists in versions 2.3.1 to 2.11.0 of the library. This issue arises from the extractPart function allocating a byte slice directly from an attacker-controlled CFB directory-entry size before validating the sector chain or size domain. Successful exploitation can lead to a panic or exhaustion of process memory. The vulnerability can be exploited by crafting a malicious OLE compound file with a negative or extremely large EncryptionInfo or EncryptedPackage stream size.

Defensive priority

Defenders should prioritize verifying the Excelize library version and applying patches or workarounds to prevent exploitation.

Recommended defensive actions

• Verify the Excelize library version and check if it is within the affected range (2.3.1 to 2.11.0).
• Apply patches or workarounds provided by the vendor to fix the vulnerability.
• Monitor for suspicious activity and implement compensating controls 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.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The vulnerability is caused by the extractPart function allocating a byte slice directly from an attacker-controlled CFB directory-entry size before validating the sector chain or size domain. The extractPart function trusts the CFB directory entry streamSize for EncryptionInfo and EncryptedPackage allocations before validating the stream. When a crafted OLE compound file declares a negative or extremely large EncryptionInfo or EncryptedPackage stream size, the declared size reaches make with a negative length or forces a multi-gigab

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.