CVE-2026-13311: shell-quote parse() is quadratic in token count, enabling denial of service

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-25 · updated 2026-10-25
Weakness: CWE-407

Description

shell-quote prior to 1.8.5 finalizes parsed tokens in parse() using Array.prototype.concat as a reduce accumulator, which reallocates and copies the entire growing array on every iteration. As a result parse() runs in O(n^2) time relative to the number of input tokens. An attacker who can supply an attacker-controlled string to any code path that calls parse() (no shell metacharacters are required; plain space-separated words suffice) can block the single-threaded Node.js event loop for an extended period with a small input, resulting in a denial of service. There is no code execution or data disclosure; impact is to availability only. Fixed in 1.8.5.

Affected products

ljharb shell-quote: before 1.9.0 — fixed in 1.9.0

How to fix

Upgrade to a fixed version: ljharb shell-quote 1.9.0. Check the vendor advisory for mitigations.

References

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