CVE-2026-107216 in Excelize
Summary
by MITRE • 10/07/2026
Excelize is a Go language library for reading and writing Microsoft Excel spreadsheets. From 2.8.1 to 2.11.0, ANCHORARRAY recursively calls the exported CalcCellValue function, creating a fresh calculation context at each cycle and bypassing in-flight and iteration controls. ANCHORARRAY calls CalcCellValue instead of cellResolver, so each recursive hop receives a new calcContext and loses cycle state. When mutually referencing dynamic-array formulas are evaluated directly or through formula-evaluating APIs, each recursion hop resets the cycle budget and prevents completion-based caches from breaking the cycle, allowing an attacker to cause a fatal Go stack overflow and abort the process. No fixed version is available as of this review.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified in Excelize versions 2.8.1 through 2.11.0 represents a critical logic flaw within the library's formula evaluation engine, specifically affecting the handling of ANCHORARRAY formulas which are integral to modern dynamic array functionality in Microsoft Excel spreadsheets. As a Go language library designed for reading and writing these files, Excelize must accurately interpret complex cell references and calculations. The core issue arises from an improper implementation of recursion controls during the calculation process. When processing mutually referencing dynamic-array formulas, either directly or through formula-evaluating APIs, the system fails to maintain state across recursive calls. This architectural oversight allows for a denial-of-service condition that can crash the host application by exhausting available stack space.
The technical root cause lies in how the ANCHORARRAY function interacts with the CalcCellValue exportable function during evaluation cycles. In a properly secured implementation, formula resolution should utilize internal mechanisms like cellResolver to maintain continuity of state and enforce iteration limits. However, Excelize incorrectly invokes CalcCellValue for each recursive step associated with ANCHORARRAY processing. This invocation creates a fresh calculation context at every cycle rather than reusing an existing one that tracks progress and constraints. Consequently, the system loses critical cycle state information required to detect circular dependencies or infinite loops. Each recursion hop effectively resets the internal budget allocated for detecting cycles, rendering any completion-based caching mechanisms ineffective in breaking the loop early.
This design flaw leads directly to a fatal Go stack overflow when an attacker provides a maliciously crafted Excel file containing mutually referencing dynamic-array formulas. Because each recursive call generates new context and discards previous cycle tracking data, the application cannot identify that it is trapped in an infinite recursion pattern. The process continues consuming memory on the execution stack until the limit is reached, causing the Go runtime to abort with a panic. This results in immediate service disruption for any system relying on Excelize to parse or generate such documents, impacting availability and potentially leading to data loss if unsaved work is involved.
From a classification perspective, this vulnerability aligns with CWE-674, which describes Uncontrolled Recursion, as the application fails to limit the depth of recursive operations based on proper state tracking. It also relates to CWE-1321, where improper handling of recursion leads to resource exhaustion. In terms of offensive security frameworks, this flaw can be leveraged within ATT&CK technique T1496, Resource Hijacking, specifically under sub-technique for Denial of Service via computational exhaustion. The attacker does not need remote code execution capabilities; simply providing a crafted file triggers the vulnerability upon processing.
Mitigation strategies are currently limited due to the absence of an official fixed version as noted in the review period. Organizations relying on Excelize must implement external safeguards to protect against this threat vector. One effective approach is to wrap formula evaluation calls within Go's recover mechanism, allowing the application to catch stack overflow panics and handle them gracefully without crashing the entire process. Additionally, implementing a custom recursion depth limiter before invoking CalcCellValue can prevent excessive nesting levels from being processed. For high-risk environments, it may be necessary to restrict input sources or validate spreadsheet structures against known safe patterns before passing them to the Excelize engine until an upstream patch is released by the maintainers.