GHSA-p2f4-r6v6-j797: electron-updater: Cross-origin redirect leaks `PRIVATE-TOKEN` and mixed-case `Authorization` credentials in `builder-util-runtime`

Summary In electron-builder's builder-util-runtime package, the HTTP redirect handler (HttpExecutor.prepareRedirectUrlOptions) only stripped a credential header whose key string matched exactly lowercase "authorization". Other credential-bearing headers — most notably PRIVATE-TOKEN (used by GitLab's personal access token flow) and mixed-case Authorization (used by GitLab's Bearer/OAuth flow) — were not stripped and could be forwarded to an attacker-controlled cross-origin redirect destination. Details Root cause HttpExecutor.prepareRedirectUrlOptions (introduced in builder-util-runtime via PR #9211, first released in v26.0.20) performed its cross-origin credential strip with a single case-sensitive property check: // vulnerable code (electron-builder v26.0.20 – v26.14.x) [via builder-util-runtime <9.7.0] if (headers?.authorization) { if (HttpExecutor.isCrossOriginRedirect(originalUrl, parsedRedirectUrl)) { delete headers.authorization // only removes the exact key "authorization" } } JavaScript object property access is case-sensitive. The guard headers?.authorization evaluates to undefined (falsy) when the key is "Authorization", "AUTHORIZATION", or any other casing, so the branch is never entered and no header is deleted for those cases. Affected updater flows The clearest reproduced path is the private GitLab updater flow. packages/electron-updater/src/providers/GitLabProvider.ts sets one of two credential headers depending on the token type: // GitLabProvider.setAuthHeaderForToken (affected versions) if (token.startsWith("Bearer")) { headers.authorization = token // Bearer / OAuth token → key is lowercase } else { headers["PRIVATE-TOKEN"] = token // personal access token → key is "PRIVATE-TOKEN" } During a private release update check, the updater requests a release asset through GitLab's direct_asset_url. GitLab commonly redirects asset downloads to an external object-storage origin (e.g., S3, GCS). Because the redirect crosses origins: 1. A persona