diff --git a/cli/release-core/http.js b/cli/release-core/http.js
index 14d411f746..3f4d45ffa3 100644
--- a/cli/release-core/http.js
+++ b/cli/release-core/http.js
@@ -60,7 +60,18 @@ function evaluateRedirect(currentUrl, location, options = {}) {
     }
   }
 
-  const originalHostname = new URL(options.originalUrl || currentUrl).hostname
+  const originalUrl = new URL(options.originalUrl || currentUrl)
+  const originalHostname = originalUrl.hostname
+
+  if (target.username || target.password) {
+    return { ok: false, reason: 'Refusing redirect containing URL credentials' }
+  }
+  if (target.port !== originalUrl.port) {
+    return {
+      ok: false,
+      reason: `Refusing redirect to unexpected port ${target.port || '(default)'}`,
+    }
+  }
   if (!isRedirectHostAllowed(target.hostname, originalHostname)) {
     return {
       ok: false,
diff --git a/cli/release-core/launcher.js b/cli/release-core/launcher.js
index d830cf074e..f82b79efcc 100644
--- a/cli/release-core/launcher.js
+++ b/cli/release-core/launcher.js
@@ -101,13 +101,18 @@ function resolveDownloadOrigin(configuredOrigin, { warn = () => {} } = {}) {
   const isHttp = parsed.protocol === 'http:' || parsed.protocol === 'https:'
   // Only an origin: credentials or a query would ride along on every request.
   const isBareOrigin =
-    !parsed.username && !parsed.password && !parsed.search && !parsed.hash
+    parsed.pathname === '/' &&
+    !parsed.username &&
+    !parsed.password &&
+    !parsed.search &&
+    !parsed.hash
   if (isHttp && isLocal && isBareOrigin) {
     return trimmed
   }
   if (
     parsed.protocol === 'https:' &&
     isReleaseOriginHost(parsed.hostname) &&
+    !parsed.port &&
     isBareOrigin
   ) {
     return trimmed
diff --git a/cli/src/__tests__/release/proxy-http-get.test.ts b/cli/src/__tests__/release/proxy-http-get.test.ts
index 13858cef41..be515ac560 100644
--- a/cli/src/__tests__/release/proxy-http-get.test.ts
+++ b/cli/src/__tests__/release/proxy-http-get.test.ts
@@ -334,6 +334,43 @@ for (const helperModule of helperModules) {
       expect(httpsGetCalls.every((call) => call.agent != null)).toBe(true)
     })
 
+    test('refuses redirect credentials and unexpected ports', async () => {
+      for (const location of [
+        'https://user:pass@github.com/releases/freebuff.tar.gz',
+        'https://github.com:444/releases/freebuff.tar.gz',
+      ]) {
+        let callCount = 0
+        const { createReleaseHttpClient } = require(helperModule.path)
+        const client = createReleaseHttpClient({
+          env: {},
+          userAgent: 'release-test-agent',
+          requestTimeout: 2500,
+          httpsModule: {
+            get(_options: unknown, callback: (response: Readable) => void) {
+              callCount += 1
+              queueMicrotask(() => {
+                callback(createResponse(302, { location }))
+              })
+              return {
+                on() {
+                  return this
+                },
+                setTimeout() {
+                  return this
+                },
+                destroy() {},
+              }
+            },
+          },
+        })
+
+        await expect(
+          client.httpGet('https://codebuff.com/api/releases/download/file'),
+        ).rejects.toMatchObject({ code: 'EREDIRECT_REFUSED' })
+        expect(callCount).toBe(1)
+      }
+    })
+
     test('limits redirect chains', async () => {
       const { createReleaseHttpClient } = require(helperModule.path)
       let callCount = 0
diff --git a/cli/src/__tests__/release/wrapper-safety.test.ts b/cli/src/__tests__/release/wrapper-safety.test.ts
index 26ac6f9062..168480b2d2 100644
--- a/cli/src/__tests__/release/wrapper-safety.test.ts
+++ b/cli/src/__tests__/release/wrapper-safety.test.ts
@@ -166,7 +166,30 @@ for (const wrapper of wrappers) {
 
 describe('shared release launcher safety', () => {
   const launcherPath = join(repoRoot, 'cli/release-core/launcher.js')
-  const { createLauncher } = require(launcherPath)
+  const { createLauncher, resolveDownloadOrigin, DEFAULT_DOWNLOAD_ORIGIN } =
+    require(launcherPath)
+
+  test('rejects release URL overrides with a path or nonstandard public port', () => {
+    const warnings: string[] = []
+
+    expect(
+      resolveDownloadOrigin('https://freebuff.com/api', {
+        warn: (message: string) => warnings.push(message),
+      }),
+    ).toBe(DEFAULT_DOWNLOAD_ORIGIN)
+    expect(
+      resolveDownloadOrigin('https://codebuff.com:8443', {
+        warn: (message: string) => warnings.push(message),
+      }),
+    ).toBe(DEFAULT_DOWNLOAD_ORIGIN)
+    expect(warnings).toHaveLength(2)
+  })
+
+  test('accepts a bare loopback origin with a custom port for local development', () => {
+    expect(resolveDownloadOrigin('http://127.0.0.1:43127')).toBe(
+      'http://127.0.0.1:43127',
+    )
+  })
 
   test('stages an update before stopping the running process', () => {
     const source = readFileSync(launcherPath, 'utf8')