From c68f36f1edb0406837527262b21cd34f18f02c0f Mon Sep 17 00:00:00 2001
From: ncihxaonn <189932551+ncihxaonn@users.noreply.github.com>
Date: Thu, 3 Sep 2026 11:43:56 +1000
Subject: [PATCH] fix: harden upstream cookie and git metadata reads

---
 CHANGELOG.md                     |  3 +++
 src/lib/cookies.ts               | 15 ++++++++++++---
 src/lib/version.ts               | 23 +++++++++++++++++++----
 tests/unit/bird-baseline.test.ts | 20 ++++++++++++++++++++
 4 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 554f4c1..879421c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -31,6 +31,9 @@
 - JSON and release-scan reads use opened file handles with identity checks to
   prevent path-swap races.
 - raw X news responses are no longer written to a debug file.
+- browser cookies are accepted only from exact X/Twitter domains or their
+  subdomains; lookalike suffixes are rejected.
+- Git worktree metadata is read through a stable, non-symlink file descriptor.
 
 ## Upstream Bird history (retained for provenance)
 
diff --git a/src/lib/cookies.ts b/src/lib/cookies.ts
index b9c537e..f06ff59 100644
--- a/src/lib/cookies.ts
+++ b/src/lib/cookies.ts
@@ -81,17 +81,26 @@ function pickCookieValue(
   cookies: Array<{ name?: string; value?: string; domain?: string }>,
   name: (typeof TWITTER_COOKIE_NAMES)[number],
 ): string | null {
-  const matches = cookies.filter((c) => c?.name === name && typeof c.value === 'string');
+  const matchesDomain = (domain: string | undefined, expected: string): boolean => {
+    const normalized = (domain ?? '').trim().toLowerCase().replace(/^\./, '');
+    return normalized === expected || normalized.endsWith(`.${expected}`);
+  };
+  const matches = cookies.filter(
+    (cookie) =>
+      cookie?.name === name &&
+      typeof cookie.value === 'string' &&
+      (matchesDomain(cookie.domain, 'x.com') || matchesDomain(cookie.domain, 'twitter.com')),
+  );
   if (matches.length === 0) {
     return null;
   }
 
-  const preferred = matches.find((c) => (c.domain ?? '').endsWith('x.com'));
+  const preferred = matches.find((cookie) => matchesDomain(cookie.domain, 'x.com'));
   if (preferred?.value) {
     return preferred.value;
   }
 
-  const twitter = matches.find((c) => (c.domain ?? '').endsWith('twitter.com'));
+  const twitter = matches.find((cookie) => matchesDomain(cookie.domain, 'twitter.com'));
   if (twitter?.value) {
     return twitter.value;
   }
diff --git a/src/lib/version.ts b/src/lib/version.ts
index 685fb46..06d36f1 100644
--- a/src/lib/version.ts
+++ b/src/lib/version.ts
@@ -149,15 +149,26 @@ export function resolveGitSha(importMetaUrl?: string): string | null {
   let dir = resolveStartDir(importMetaUrl);
   for (let i = 0; i < 10; i += 1) {
     const dotGit = path.join(dir, '.git');
+    let descriptor: number | null = null;
     try {
-      const stat = fs.statSync(dotGit);
-      if (stat.isDirectory()) {
+      const noFollow = process.platform === 'win32' ? 0 : fs.constants.O_NOFOLLOW;
+      descriptor = fs.openSync(dotGit, fs.constants.O_RDONLY | noFollow);
+      const openedStats = fs.fstatSync(descriptor);
+      const pathStats = fs.lstatSync(dotGit);
+      if (
+        pathStats.isSymbolicLink() ||
+        openedStats.dev !== pathStats.dev ||
+        openedStats.ino !== pathStats.ino
+      ) {
+        throw new Error('Unstable Git metadata path');
+      }
+      if (openedStats.isDirectory()) {
         const sha = resolveGitShaFromGitDir(dotGit);
         if (sha) {
           return sha;
         }
-      } else if (stat.isFile()) {
-        const txt = fs.readFileSync(dotGit, 'utf8');
+      } else if (openedStats.isFile()) {
+        const txt = fs.readFileSync(descriptor, 'utf8');
         const match = GITDIR_REGEX.exec(txt);
         const gitDir = match?.[1]?.trim();
         if (gitDir) {
@@ -170,6 +181,10 @@ export function resolveGitSha(importMetaUrl?: string): string | null {
       }
     } catch {
       // ignore
+    } finally {
+      if (descriptor !== null) {
+        fs.closeSync(descriptor);
+      }
     }
 
     const parent = path.dirname(dir);
diff --git a/tests/unit/bird-baseline.test.ts b/tests/unit/bird-baseline.test.ts
index 5056e5c..d6d7a46 100644
--- a/tests/unit/bird-baseline.test.ts
+++ b/tests/unit/bird-baseline.test.ts
@@ -207,6 +207,26 @@ describe('Bird credential resolution baseline', () => {
     expect(getCookiesMock.mock.calls.map(([input]) => input.browsers)).toEqual([['safari'], ['chrome']]);
   });
 
+  it('rejects lookalike cookie domains and accepts exact X domains', async () => {
+    getCookiesMock.mockResolvedValue({
+      cookies: [
+        { name: 'auth_token', value: 'lookalike-auth', domain: 'notx.com' },
+        { name: 'ct0', value: 'lookalike-ct0', domain: 'eviltwitter.com' },
+        { name: 'auth_token', value: 'browser-auth', domain: '.x.com' },
+        { name: 'ct0', value: 'browser-ct0', domain: 'api.x.com' },
+      ],
+      warnings: [],
+    });
+
+    const result = await resolveCredentials({ cookieSource: 'chrome' });
+
+    expect(result.cookies).toMatchObject({
+      authToken: 'browser-auth',
+      ct0: 'browser-ct0',
+      source: 'Chrome default profile',
+    });
+  });
+
   it('documents the upstream environment-before-browser priority', async () => {
     process.env.AUTH_TOKEN = 'env-auth';
     process.env.CT0 = 'env-ct0';