http4s up to 0.23.34/1.0.0-M46 ResponseCookie ResponseCookie.render injection

Summaryinfo

A vulnerability was found in http4s up to 0.23.34/1.0.0-M46. It has been rated as critical. Affected is the function ResponseCookie.render of the component ResponseCookie. The manipulation leads to injection. This vulnerability is traded as CVE-2026-69211. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, has been found in http4s up to 0.23.34/1.0.0-M46. This issue affects the function ResponseCookie.render of the component ResponseCookie. The manipulation with an unknown input leads to a injection vulnerability. Using CWE to declare the problem leads to CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, ResponseCookie.render writes attacker-influenced name, content, domain, path, and extension values without neutralizing semicolons or control characters. An application that constructs a ResponseCookie from unvalidated input can therefore emit injected cookie attributes such as Domain, Path, or SameSite, widening cookie scope or weakening protections, and control characters may enable header splitting on permissive backends. The patch strips control characters from all five fields and strips semicolons from name, content, domain, and path while retaining the extension delimiter behavior. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-69211 since 08/03/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1055 according to MITRE ATT&CK.

Upgrading to version 0.23.35 or 1.0.0-M47 eliminates this vulnerability.

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Productinfo

Name

• http4s

Version

• 0.23.0
• 0.23.1
• 0.23.2
• 0.23.3
• 0.23.4
• 0.23.5
• 0.23.6
• 0.23.7
• 0.23.8
• 0.23.9
• 0.23.10
• 0.23.11
• 0.23.12
• 0.23.13
• 0.23.14
• 0.23.15
• 0.23.16
• 0.23.17
• 0.23.18
• 0.23.19
• 0.23.20
• 0.23.21
• 0.23.22
• 0.23.23
• 0.23.24
• 0.23.25
• 0.23.26
• 0.23.27
• 0.23.28
• 0.23.29
• 0.23.30
• 0.23.31
• 0.23.32
• 0.23.33
• 0.23.34
• 1.0.0-M46

Website

• Product: https://github.com/http4s/http4s/

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