CVE-2026-82731Unescaped path parameters in AshTypescript generated TypeScript client allow request redirection

Official description

URL Redirection to Untrusted Site ('Open Redirect') vulnerability in ash-project ash_typescript allows an attacker who controls a path-parameter value to redirect a generated client's request, and the credentials attached to it, to an unintended route or an external origin. The URL builders in lib/ash_typescript/typed_controller/codegen/route_renderer.ex replace each :param placeholder with a bare template interpolation and never call encodeURIComponent, so the value reaches executeTypedControllerRequest raw. A value containing ../ is normalised away by the fetch URL resolver and reaches a different route, while ? or # truncates the path and can smuggle or override query parameters. For a route whose path begins with a parameter, a value such as /evil.example.com/x yields the protocol-relative URL //evil.example.com/x, sending the request and the credentials from TypedControllerConfig to an attacker-controlled host. Nothing constrains the value at runtime: get_path_param_type/2 emits only a TypeScript type, which is erased. The query-string path is unaffected, since URLSearchParams.set encodes its own values. This issue affects ash_typescript: from 0.15.0 before 0.18.0.

Affected products (as reported)

References

• https://github.com/ash-project/ash_typescript/security/advisories/GHSA-6g23-p936-fm2f related, vendor-advisory
• https://cna.erlef.org/cves/CVE-2026-82731.html related
• https://osv.dev/vulnerability/EEF-CVE-2026-82731 related
• https://github.com/ash-project/ash_typescript/commit/5165f752f5f92b755d946f2d1ce750ff69083ffc patch