Effect-TS effect platform Cookie Serialization makeCookie name/domain/path response splitting

Summaryinfo

A vulnerability identified as critical has been detected in Effect-TS effect platform. This affects the function makeCookie of the component Cookie Serialization. This manipulation of the argument name/domain/path causes response splitting. This vulnerability appears as CVE-2026-115779. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability has been found in Effect-TS effect platform (affected version not known) and classified as critical. Affected by this vulnerability is the function makeCookie of the component Cookie Serialization. The manipulation of the argument name/domain/path with an unknown input leads to a response splitting vulnerability. The CWE definition for the vulnerability is CWE-113. The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-115779 since 10/23/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/03/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• Effect-TS

Name

• effect platform

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

Discussion