Executive Summary
The CVE-2026-14257 vulnerability poses a significant threat due to its high severity and relatively low attack complexity, making it likely to be exploited. Its impact could be substantial, leading to denial-of-service conditions in affected applications. Given its severity and potential for exploitation, it is crucial for organizations to address this vulnerability promptly.
Enhanced Description
The fix for this vulnerability, as implemented in version 5.0.8 of brace-expansion, introduces a maxLength option (defaulting to 4,000,000) that effectively bounds the accumulated output and intermediate arrays. This addition serves as a critical mitigation measure, preventing the uncontrolled memory growth that previously led to out-of-memory errors. It underscores the importance of validating and bounding input and output lengths in functions dealing with potentially expansive operations like brace expansion, to prevent similar vulnerabilities from arising in the future.
Exploitation Context
Realistic exploitation scenarios for this vulnerability include attacks on web applications or services that utilize the vulnerable brace-expansion library, where an attacker could submit crafted input designed to trigger the DoS condition. The motivation for attackers to exploit this vulnerability would likely be to disrupt service availability or to use the vulnerability as part of more complex attacks, leveraging the DoS as a smokescreen or distraction.
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Confidence Assessment
The confidence in the severity rating of this vulnerability is high, given its demonstrated potential to cause significant denial-of-service conditions with relatively minimal input. The likelihood of exploitation is also considered high due to the low attack complexity and the potential for attackers to leverage this vulnerability in various scenarios.
brace-expansion through 5.0.7 is vulnerable to denial of service via memory exhaustion. The expand() function limits the number of results with a max option (default 100,000) but does not bound the length of each result string. By chaining multiple brace groups, an attacker keeps the result count under the limit while making each result progressively longer, so total memory scales with both count and string length until the process hits a fatal, uncatchable out-of-memory error. About 7.5 KB of input ('{a,b}'.repeat(1500)) crashes a default Node.js process. Any application that passes attacker-influenced strings to brace-expansion.expand() - directly or transitively via minimatch / glob brace patterns - can be crashed by a small request. Fixed in 5.0.8 by adding a maxLength option (default 4,000,000) that bounds accumulated output and intermediate arrays.
26.7th percentile