Effect: Cookie attribute injection via domain, path, and name fields in @effect/platform makeCookie()

published 2026-11-03 5 d ago modified 2026-11-03 5 d ago also EUVD-2026-116496

cvss: 6.3; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.6%; EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits: 0; none known

Effect is a TypeScript framework that consists of several packages that work together to help build TypeScript applications. From @effect/platform 0.1.0 until 0.97.1 and effect 4.0.0-beta.0 until 4.0.0-beta.103, the name, domain, and path fields passed to makeCookie() allow semicolon delimiters that serializeCookie() writes verbatim into Set-Cookie headers. A caller that supplies attacker-controlled values can append cookie attributes, including a broader Domain or, when the caller has not set those options itself, SameSite=None or Max-Age. Encoded cookie values and CR or LF characters remain unaffected. This can widen a cookie's scope or add otherwise-unset cookie attributes. This issue is fixed in @effect/platform 0.97.1 and effect 4.0.0-beta.103.

Patch / fix

links 6

github.com/Effect-TS/effect@4a57af2 commit
github.com/Effect-TS/effect@5859b37 commit
github.com/Effect-TS/effect#6763 pull request
github.com/Effect-TS/effect#6765 pull request
github.com/Effect-TS/effect/releases/tag/@effect/platform@0.97.1 release
github.com/Effect-TS/effect/releases/tag/effect@4.0.0-beta.103 release

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 5 d ago (2026-11-03)

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	6.3	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
CNA	4.0	6.3	CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/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

Affected products

Effect-TS effect
@effect platform

Classification

Weakness

CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component

References

Sources

CVE List CVE-2026-115779
NVD CVE-2026-115779

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary