AIKIDO-2026-106555
@sveltejs/kit is vulnerable to Regular Expression Denial of Service (ReDoS)
53
Medium Risk
This Affects:
@sveltejs/kitTL;DR
SvelteKit performs HTTP content negotiation by parsing the Accept request header with a regular expression in its content-negotiation utility. The regular expression is unanchored, so a specially crafted Accept header value triggers catastrophic backtracking and quadratic processing time. Requests carrying such headers force the server to spend excessive CPU on a single request, producing a remote denial of service where platform header-length limits are raised or absent. The fix anchors the regular expression so Accept header parsing runs in linear time.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and your deployment allows large Accept request headers because platform header-length limits are raised or absent.
Background info
@sveltejs/kit is vulnerable to Regular Expression Denial of Service (ReDoS) in versions 0.0.1 - 2.70.1.
How to fix this
Upgrade the @sveltejs/kit library to the patch version.
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SOC 2Compliant
ISO 27001Compliant