CVE-2026-123561 · Package
NO FIX YET · SEE WHAT TO DO
devalue is a JavaScript library for serializing and parsing data, and before 5.9.3 a malformed null-prototype object key can slip past its __proto__ rejection during property-key coercion. The sources say this yields objects with an own __proto__ property, which by itself does not cause prototype pollution.
first public Sep 18, 2026 · 1 source
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Applications that call devalue's parse on data an outside party can supply, such as request bodies or stored payloads, are the ones that matter. Projects that only serialize trusted data or never parse untrusted input are less exposed. The sources do not describe a specific downstream exploit path beyond the bypass itself.
Not affected if trusted-input-only
Who cares devalue, javascript, npm
npm ls devalue to find the installed version in each projectdevalue version in package-lock.json, pnpm-lock.yaml or yarn.lock5.9.3 or laterdevalue before 5.9.3 allows malformed null-prototype object keys to bypass parse's proto rejection through property-key coercion, an incomplete fix for GHSA-mwv9-gp5h-frr4. Attackers can supply crafted payloads that yield objects with a proto own property, which alone does not cause prototype pollution.
This page as .md · .json · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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