CVE-2026-53531 in RaTeX
Summary
by MITRE • 08/22/2026
RaTeX is a KaTeX-compatible math rendering engine written in Rust. Prior to version 0.1.11, RaTeX’s recursive-descent parser recurses one (or more) native stack frame per nesting level at `{`, `\left`, `\sqrt{`, `^{`, etc, with no maximum depth limit. A short, ~10 KB input of nested groups overflows the 8 MB main-thread stack and aborts the process. With `panic = "abort"` (`Cargo.toml:48`), and because a Rust stack overflow is always a fatal `SIGABRT` regardless of panic strategy this is an unrecoverable, whole-process denial of service reachable from a single untrusted LaTeX string. Version 0.1.11 fixes the issue.
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Analysis
by VulDB Data Team • 08/22/2026
The vulnerability identified in RaTeX prior to version 0.1.11 represents a critical resource exhaustion flaw stemming from an unrestricted recursive descent parsing mechanism. As a math rendering engine compatible with KaTeX and implemented in Rust, RaTeX is designed to process LaTeX-formatted mathematical expressions for display in web applications or other software interfaces. The core issue lies in the parser's architecture, which allocates one native stack frame per nesting level encountered during the processing of specific syntax elements such as curly braces `{`, left delimiters `\left`, square roots `\sqrt{}`, and superscripts `^{}`. This design choice creates a direct correlation between the depth of mathematical expression nesting and the amount of memory consumed on the call stack, without any implemented safeguards to limit recursion depth.
From a technical perspective, this flaw constitutes an uncontrolled resource consumption vulnerability that leads directly to application crashes. When an attacker provides a maliciously crafted input string containing deeply nested groups, the parser recursively invokes itself for each level of nesting. Because Rust's default behavior on stack overflow is to trigger a fatal SIGABRT signal regardless of the panic strategy configured in Cargo.toml, this results in an immediate and unrecoverable termination of the entire process. The threshold for triggering this crash is remarkably low; inputs as small as approximately 10 KB can exhaust the standard 8 MB main-thread stack limit. This means that even relatively short strings, which might appear benign or typical in complex mathematical contexts, are sufficient to cause a denial of service if they contain excessive nesting depth.
The operational impact of this vulnerability is severe for any system relying on RaTeX to render untrusted user input. Since the crash affects the entire process rather than just the thread handling the specific request, it can lead to widespread availability issues in multi-threaded environments where shared resources or global state might be corrupted upon abrupt termination. This aligns with Common Weakness Enumeration CWE-787, which classifies out-of-bounds writes and stack overflows as critical integrity and availability risks. Furthermore, this vulnerability is exploitable via a single untrusted LaTeX string, making it particularly dangerous in web-facing applications where user input is directly processed by the rendering engine without prior sanitization or depth validation.
In terms of threat modeling, this attack vector maps to MITRE ATT&CK technique T1496, Resource Hijacking, specifically under sub-techniques involving denial of service through resource exhaustion. The attacker leverages the application's own parsing logic against it, forcing the system into a state where it cannot continue normal operations due to stack overflow conditions. This is distinct from memory leak vulnerabilities because the impact is immediate and catastrophic rather than gradual degradation.
Mitigation for this vulnerability was addressed in version 0.1.11 of RaTeX by implementing limits on recursion depth or refactoring the parser to use heap-based data structures instead of relying solely on native stack frames for deep nesting scenarios. For systems still running older versions, immediate upgrade is required. In interim situations where upgrading is not feasible, input validation mechanisms should be implemented at the application layer to detect and reject LaTeX strings with excessive nesting levels before they reach the RaTeX parser. Additionally, configuring runtime environment limits such as ulimit on Unix-like systems can provide a secondary layer of defense by capping stack size, although this may impact legitimate use cases requiring deep recursion and is not a substitute for fixing the underlying parsing logic.