From 773da036bda0ef5155607fceb4abc9d6f4671063 Mon Sep 17 00:00:00 2001
From: ArianAr <arian.fawiki@gmail.com>
Date: Thu, 16 Jul 2026 00:29:08 +0300
Subject: [PATCH] fix(security): clear remaining CodeQL workflow and ReDoS
 alerts
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- CI: explicit permissions.contents: read (missing-workflow-permissions)
- stripAnsi: linear scan instead of nested quantifier regexes
  (js/polynomial-redos); incomplete OSC no longer eats trailing text

Addresses code scanning alerts #2, #6–#11.
---
 .github/workflows/ci.yml    |  4 ++
 CHANGELOG.md                |  2 +
 server/lib/metadata.test.ts | 20 ++++++++++
 server/lib/metadata.ts      | 76 ++++++++++++++++++++++++++++++++++---
 4 files changed, 97 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8a720eb..255c543 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,6 +10,10 @@ concurrency:
   group: ci-${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
+# Least privilege: jobs only need to read the repo (no write tokens).
+permissions:
+  contents: read
+
 env:
   NEXT_TELEMETRY_DISABLED: "1"
   CI: "true"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c5c0331..21eebb1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Theme FOUC boot script is a static string (no `JSON.stringify` interpolation) to clear CodeQL `js/bad-code-sanitization`
+- CI workflow sets explicit `permissions: contents: read` (CodeQL `actions/missing-workflow-permissions`)
+- `stripAnsi` uses a linear scan instead of nested quantifier regexes (CodeQL `js/polynomial-redos`)
 
 ### Planned
 
diff --git a/server/lib/metadata.test.ts b/server/lib/metadata.test.ts
index ffe7f65..0b4213b 100644
--- a/server/lib/metadata.test.ts
+++ b/server/lib/metadata.test.ts
@@ -10,6 +10,26 @@ describe("stripAnsi", () => {
   it("removes CSI color sequences", () => {
     expect(stripAnsi("\u001b[31merror\u001b[0m")).toBe("error");
   });
+
+  it("removes OSC sequences terminated by BEL or ST", () => {
+    expect(stripAnsi("\u001b]0;title\u0007plain")).toBe("plain");
+    expect(stripAnsi("\u001b]8;;https://ex\u001b\\link")).toBe("link");
+  });
+
+  it("removes two-byte Fe sequences and lone ESC", () => {
+    expect(stripAnsi("a\u001bMb")).toBe("ab");
+    expect(stripAnsi("x\u001by")).toBe("xy");
+  });
+
+  it("handles incomplete sequences without hanging", () => {
+    // Incomplete CSI: drop from ESC to end (no final byte)
+    expect(stripAnsi("\u001b[31")).toBe("");
+    // Incomplete OSC: drop ESC] only; keep following plain text
+    expect(stripAnsi("\u001b]noend")).toBe("noend");
+    // Many ESC] prefixes without terminators (former ReDoS shape)
+    const hostile = `${"\u001b]".repeat(200)}text`;
+    expect(stripAnsi(hostile)).toBe("text");
+  });
 });
 
 describe("detectLogLevel", () => {
diff --git a/server/lib/metadata.ts b/server/lib/metadata.ts
index babb14b..5a7eac0 100644
--- a/server/lib/metadata.ts
+++ b/server/lib/metadata.ts
@@ -30,12 +30,78 @@ const BRACKETED_LEVEL_RE =
 const LEADING_LEVEL_RE =
   /^\s*(?:[\d\-T:.Z]+\s+)?(?:\[)?(FATAL|ERROR|WARN(?:ING)?|INFO|DEBUG|TRACE)(?:\])?\b/i;
 
-/** Strip common ANSI CSI / OSC sequences for metadata and search. */
+/**
+ * Strip common ANSI CSI / OSC / 2-byte sequences for metadata and search.
+ * Hand-rolled linear scan (no nested quantifiers) to avoid ReDoS on hostile input.
+ */
 export function stripAnsi(input: string): string {
-  return input
-    .replace(/\u001b\][\s\S]*?(?:\u0007|\u001b\\)/g, "")
-    .replace(/\u001b\[[0-9;?]*[ -/]*[@-~]/g, "")
-    .replace(/\u001b[@-Z\\-_]/g, "");
+  let out = "";
+  let i = 0;
+  const n = input.length;
+
+  while (i < n) {
+    if (input.charCodeAt(i) !== 0x1b /* ESC */) {
+      out += input[i]!;
+      i += 1;
+      continue;
+    }
+
+    const next = i + 1 < n ? input.charCodeAt(i + 1) : -1;
+
+    // CSI: ESC [ ... final byte in @-~
+    if (next === 0x5b /* [ */) {
+      i += 2;
+      while (i < n) {
+        const c = input.charCodeAt(i);
+        i += 1;
+        if (c >= 0x40 && c <= 0x7e) break;
+      }
+      continue;
+    }
+
+    // OSC: ESC ] ... BEL (0x07) or ST (ESC \)
+    // Incomplete OSC (no terminator) only drops ESC] — never eats following text.
+    if (next === 0x5d /* ] */) {
+      const bodyStart = i + 2;
+      let j = bodyStart;
+      let terminatedAt = -1;
+      while (j < n) {
+        const c = input.charCodeAt(j);
+        if (c === 0x07) {
+          terminatedAt = j + 1;
+          break;
+        }
+        if (c === 0x1b) {
+          if (j + 1 < n && input.charCodeAt(j + 1) === 0x5c /* \ */) {
+            terminatedAt = j + 2; // ST
+          }
+          // Else another ESC: abort body; outer loop reprocesses from j.
+          break;
+        }
+        j += 1;
+      }
+      if (terminatedAt !== -1) {
+        i = terminatedAt;
+      } else if (j < n && input.charCodeAt(j) === 0x1b) {
+        i = j;
+      } else {
+        // EOF without terminator — keep body as plain text
+        i = bodyStart;
+      }
+      continue;
+    }
+
+    // 2-byte Fe sequences: ESC @ through ESC _
+    if (next >= 0x40 && next <= 0x5f) {
+      i += 2;
+      continue;
+    }
+
+    // Lone ESC — drop it
+    i += 1;
+  }
+
+  return out;
 }
 
 function normalizeLevel(raw: string): Exclude<LogLevel, "UNKNOWN"> {