LiquidJS is a Shopify / GitHub Pages compatible template engine in pure JavaScript. Prior to version 10.25.1, the replace_first filter in LiquidJS uses JavaScript's String.prototype.replace() which interprets $& as a back reference to the matched substring. The filter only charges memoryLimit for the input string length, not the amplified output. An attacker can achieve exponential memory amplification (up to 625,000:1) while staying within the memoryLimit budget, leading to denial of service. Version 10.25.1 patches the issue.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:NA:H7.5/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HInput Validation
Resource Management