CVE-2026-21717

Name	CVE-2026-21717
Description	A flaw in V8's string hashing mechanism causes integer-like strings to be hashed to their numeric value, making hash collisions trivially predictable. By crafting a request that causes many such collisions in V8's internal string table, an attacker can significantly degrade performance of the Node.js process. The most common trigger is any endpoint that calls `JSON.parse()` on attacker-controlled input, as JSON parsing automatically internalizes short strings into the affected hash table. This vulnerability affects 20.x, 22.x, 24.x, and 25.x.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DSA-6183-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
nodejs (PTS)	bullseye	12.22.12~dfsg-1~deb11u4	vulnerable
	bullseye (security)	12.22.12~dfsg-1~deb11u7	vulnerable
	bookworm, bookworm (security)	18.20.4+dfsg-1~deb12u1	vulnerable
	trixie	20.19.2+dfsg-1	vulnerable
	trixie (security)	20.19.2+dfsg-1+deb13u2	fixed
	forky, sid	22.22.2+dfsg+~cs22.19.15-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
nodejs	source	trixie	20.19.2+dfsg-1+deb13u2		DSA-6183-1
nodejs	source	(unstable)	22.22.2+dfsg+~cs22.19.15-1

Notes

https://nodejs.org/en/blog/vulnerability/march-2026-security-releases#hashdos-in-v8-cve-2026-21717---medium
Fixed by: https://github.com/nodejs/node/commit/af5c144ebcf9814ef5dc74555bbdcd2a4cb20a12 (v20.20.2)