CVE-2026-88038

Medium

Description

cookies is a Node.js library for reading and writing HTTP cookies, used by Koa via ctx.cookies. In versions before 0.9.2 the library validates the cookie name and value against character sets that reject the semicolon separator, but the domain and path options are checked only against a permissive RFC 7230 field-content matcher that allows semicolons, and both are written into the Set-Cookie header unescaped. An application that passes untrusted or request-derived data into the domain or path option can therefore inject additional cookie attributes, overriding SameSite, Secure, HttpOnly, or Domain on the cookies the application issues. This is a Set-Cookie attribute injection issue (CWE-74). The issue is fixed in cookies 0.9.2, which validates domain and path against RFC 6265 character sets. As a workaround, keep domain and path application-set rather than derived from untrusted input.

SeverityMedium
CVSS4.8
Exploit probability—
ProductCookies
PublishedSep 10, 2026
First seenSep 10, 2026
Weakness typeCWE-74Injection

How to fix

Update
  • cookies cookies0.9.2 or later

Affected products

ProductAffected versionsFixed in
cookies cookiesv < 0.9.20.9.2

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CVE-2026-88038 · Cookies · Dark Radar