diff --git a/packages/opencode/src/server/shared/ui.ts b/packages/opencode/src/server/shared/ui.ts
index c2fd3b86375..d3f2c451131 100644
--- a/packages/opencode/src/server/shared/ui.ts
+++ b/packages/opencode/src/server/shared/ui.ts
@@ -9,7 +9,7 @@ let embeddedUIPromise: Promise<Record<string, string> | null> | undefined
 export const UI_UPSTREAM = new URL("https://app.opencode.ai")
 
 export const csp = (hash = "") =>
-  `default-src 'self'; script-src 'self' 'wasm-unsafe-eval'${hash ? ` 'sha256-${hash}'` : ""}; style-src 'self' 'unsafe-inline'; img-src 'self' data: https:; font-src 'self' data:; media-src 'self' data:; connect-src * data:`
+  `default-src 'self'; script-src 'self' 'wasm-unsafe-eval'${hash ? ` 'sha256-${hash}'` : ""}; style-src 'self' 'unsafe-inline'; img-src 'self' data: https: blob:; font-src 'self' data:; media-src 'self' data:; connect-src * data: blob:`
 export const DEFAULT_CSP = csp()
 
 export function themePreloadHash(body: string) {
diff --git a/packages/opencode/test/server/httpapi-ui.test.ts b/packages/opencode/test/server/httpapi-ui.test.ts
index 2f10193f3d4..1a7ccc60dab 100644
--- a/packages/opencode/test/server/httpapi-ui.test.ts
+++ b/packages/opencode/test/server/httpapi-ui.test.ts
@@ -326,7 +326,7 @@ describe("HttpApi UI fallback", () => {
     }),
   )
 
-  it.live("allows embedded UI terminal wasm and theme preload CSP", () =>
+  it.live("allows embedded UI terminal wasm, blob attachments, and theme preload CSP", () =>
     Effect.gen(function* () {
       const script = 'document.documentElement.dataset.theme = "dark"'
 
@@ -351,7 +351,8 @@ describe("HttpApi UI fallback", () => {
       const csp = response.headers.get("content-security-policy") ?? ""
       expect(csp).toContain("script-src 'self' 'wasm-unsafe-eval'")
       expect(csp).toContain(`'sha256-${createHash("sha256").update(script).digest("base64")}'`)
-      expect(csp).toContain("connect-src * data:")
+      expect(csp).toContain("img-src 'self' data: https: blob:")
+      expect(csp).toContain("connect-src * data: blob:")
     }),
   )