Excelize: extractPart allocates attacker-controlled, unbounded and negative-sized buffers from CFB directory entries: remote panic / OOM DoS

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.3.1 to 2.11.0, extractPart allocates a byte slice directly from an attacker-controlled CFB directory-entry size before validating the sector chain or size domain. extractPart 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-gigabyte allocation, allowing an attacker to panic or exhaust process memory. No fixed version is available as of this review.

[ Fixes ]Fixes and patches

• github.com/xuri/excelize/v2 2.11.1-0.20260912113515-5f636f9dcde5Fixed version · GitHub Advisories · go package github.com/xuri/excelize/v2: upgrade to 2.11.1-0.20260912113515-5f636f9dcde5 or later (affected >= 2.3.1, < 2.11.1-0.20260912113515-5f636f9dcde5)
• Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD
• Patch on github.comVendor patch or bulletin · NVD · Reference tagged 'Patch' by NVD

[ Packages ]Affected open-source packages

• github.com/xuri/excelize/v2 goAffected >= 2.3.1, < 2.11.1-0.20260912113515-5f636f9dcde5 · fixed in 2.11.1-0.20260912113515-5f636f9dcde5 · GHSA-x2q3-8cjh-766f

[ References ]References

• github.com/qax-os/excelize/commit/5f636f9dcde55911f14290060b017f0cc88cd694Patch
• github.com/qax-os/excelize/pull/2396Issue TrackingPatch
• github.com/qax-os/excelize/security/advisories/GHSA-x2q3-8cjh-766fExploitVendor Advisory