phenixdigital phoenix_storybook up to 1.0.x Template String code injection

Summaryinfo

A vulnerability, which was classified as critical, was found in phenixdigital phoenix_storybook up to 1.0.x. This vulnerability affects unknown code of the component Template String Handler. The manipulation results in code injection. This vulnerability is cataloged as CVE-2026-8467. The attack may be launched remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in phenixdigital phoenix_storybook up to 1.0.x. It has been classified as critical. Affected is some unknown functionality of the component Template String Handler. The manipulation with an unknown input leads to a code injection vulnerability. CWE is classifying the issue as CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Code Injection vulnerability in phenixdigital phoenix_storybook allows unauthenticated remote code execution via unsanitized attribute value interpolation in HEEx template generation. The psb-assign WebSocket event handler in 'Elixir.PhoenixStorybook.Story.PlaygroundPreviewLive':handle_event/3 accepts arbitrary attribute names and values from unauthenticated clients. These values are passed to 'Elixir.PhoenixStorybook.Helpers.ExtraAssignsHelpers':handle_set_variation_assign/3, which stores them verbatim. When rendering, 'Elixir.PhoenixStorybook.Rendering.ComponentRenderer':attributes_markup/1 interpolates binary attribute values directly into a HEEx template string as name="<val>" without escaping double quotes or HEEx expression delimiters. An attacker can supply a value containing a closing quote followed by a HEEx expression block (e.g. foo" injected={EXPR} bar="), which causes EXPR to be treated as an inline Elixir expression. The resulting template is compiled via EEx.compile_string/2 and executed via Code.eval_quoted_with_env/3 with full Kernel imports and no sandbox, giving the attacker arbitrary code execution on the server. This issue affects phoenix_storybook from 0.5.0 before 1.1.0.

The weakness was shared by Nick Mykhailyshyn and Cenk Kücük. The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-8467 since 05/13/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1059.

Upgrading to version 1.1.0 eliminates this vulnerability. Applying the patch 56ab8464d4375fa52db806148a06cce126ad481d is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-31112). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• phenixdigital

Name

• phoenix_storybook

Version

• 1.0

Website

• Product: https://github.com/phenixdigital/phoenix_storybook/

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Once again VulDB remains the best source for vulnerability data.

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