diff --git a/packages/deno/src/integrations/contextlines.ts b/packages/deno/src/integrations/contextlines.ts
index fe0a3708850a..e367003d8437 100644
--- a/packages/deno/src/integrations/contextlines.ts
+++ b/packages/deno/src/integrations/contextlines.ts
@@ -1,7 +1,10 @@
 import type { Event, IntegrationFn, StackFrame } from '@sentry/core';
-import { addContextToFrame, defineIntegration, LRUMap } from '@sentry/core';
+import { addContextToFrame, defineIntegration, LRUMap, stripUrlQueryAndFragment } from '@sentry/core';
 
 const INTEGRATION_NAME = 'ContextLines' as const;
+// Frame filenames come from the parsed `error.stack` string, which application
+// code can overwrite with external input, so only read source files.
+const SOURCE_FILE_EXTENSION = /\.(?:[cm]?[jt]sx?|vue|svelte|astro|mdx)$/i;
 const FILE_CONTENT_CACHE = new LRUMap<string, string | null>(100);
 const DEFAULT_LINES_OF_CONTEXT = 5;
 
@@ -91,7 +94,12 @@ async function addSourceContext(event: Event, contextLines: number): Promise<Eve
 async function addSourceContextToFrames(frames: StackFrame[], contextLines: number): Promise<void> {
   for (const frame of frames) {
     // Only add context if we have a filename and it hasn't already been added
-    if (frame.filename && frame.in_app && frame.context_line === undefined) {
+    if (
+      frame.filename &&
+      frame.in_app &&
+      frame.context_line === undefined &&
+      SOURCE_FILE_EXTENSION.test(stripUrlQueryAndFragment(frame.filename))
+    ) {
       const permission = await Deno.permissions.query({
         name: 'read',
         path: frame.filename,
diff --git a/packages/node/src/integrations/contextlines.ts b/packages/node/src/integrations/contextlines.ts
index 12cc79c90366..9ff0d22cc48f 100644
--- a/packages/node/src/integrations/contextlines.ts
+++ b/packages/node/src/integrations/contextlines.ts
@@ -1,9 +1,10 @@
 import { createReadStream } from 'node:fs';
 import { createInterface } from 'node:readline';
 import type { Event, IntegrationFn, StackFrame } from '@sentry/core';
-import { debug, defineIntegration, LRUMap, snipLine } from '@sentry/core';
+import { debug, defineIntegration, LRUMap, snipLine, stripUrlQueryAndFragment } from '@sentry/core';
 import { DEBUG_BUILD } from '../debug-build';
 
+const SOURCE_FILE_EXTENSION = /\.(?:[cm]?[jt]sx?|vue|svelte|astro|mdx)$/;
 const LRU_FILE_CONTENTS_CACHE = new LRUMap<string, Record<number, string>>(10);
 const LRU_FILE_CONTENTS_FS_READ_FAILED = new LRUMap<string, 1>(20);
 const DEFAULT_LINES_OF_CONTEXT = 5;
@@ -31,6 +32,7 @@ interface ContextLinesOptions {
  */
 export function resetFileContentCache(): void {
   LRU_FILE_CONTENTS_CACHE.clear();
+  LRU_FILE_CONTENTS_FS_READ_FAILED.clear();
 }
 
 /**
@@ -49,19 +51,22 @@ function emplace<T extends LRUMap<K, V>, K extends string, V>(map: T, key: K, co
 
 /**
  * Determines if context lines should be skipped for a file.
- * - .min.(mjs|cjs|js) files are and not useful since they dont point to the original source
  * - node: prefixed modules are part of the runtime and cannot be resolved to a file
  * - data: skip json, wasm and inline js https://nodejs.org/api/esm.html#data-imports
+ * - .min.(mjs|cjs|js) files are and not useful since they dont point to the original source
+ * - anything that is not a JavaScript or TypeScript source file. Frame filenames come
+ *   from the parsed `error.stack` string, which application code can overwrite with
+ *   external input, so we must not read arbitrary files off the filesystem.
  */
 function shouldSkipContextLinesForFile(path: string): boolean {
-  // Test the most common prefix and extension first. These are the ones we
-  // are most likely to see in user applications and are the ones we can break out of first.
   if (path.startsWith('node:')) return true;
-  if (path.endsWith('.min.js')) return true;
-  if (path.endsWith('.min.cjs')) return true;
-  if (path.endsWith('.min.mjs')) return true;
   if (path.startsWith('data:')) return true;
-  return false;
+
+  const pathname = stripUrlQueryAndFragment(path).toLowerCase();
+  if (pathname.endsWith('.min.js')) return true;
+  if (pathname.endsWith('.min.cjs')) return true;
+  if (pathname.endsWith('.min.mjs')) return true;
+  return !SOURCE_FILE_EXTENSION.test(pathname);
 }
 
 /**
diff --git a/packages/node/test/integrations/contextlines.test.ts b/packages/node/test/integrations/contextlines.test.ts
index af49e1da01cc..c8a5d17ce287 100644
--- a/packages/node/test/integrations/contextlines.test.ts
+++ b/packages/node/test/integrations/contextlines.test.ts
@@ -69,6 +69,44 @@ describe('ContextLines', () => {
     });
   });
 
+  describe('file filtering', () => {
+    test.each([
+      '/var/task/.env',
+      '/etc/passwd',
+      '/home/user/.ssh/id_rsa',
+      'file:///var/task/config.json',
+      'file:///var/task/index.js.bak',
+      'file:///var/task/index.min.js?v=abc',
+    ])('does not read non-source file %s', async filename => {
+      expect.assertions(1);
+      const frames: StackFrame[] = [{ colno: 1, filename, lineno: 1, function: 'fxn1' }];
+
+      const readStreamSpy = vi.spyOn(fs, 'createReadStream');
+      await addContext(frames);
+      expect(readStreamSpy).not.toHaveBeenCalled();
+    });
+
+    test.each([
+      'file:///var/task/index.js',
+      'file:///var/task/index.mjs',
+      'file:///var/task/index.cjs',
+      'file:///var/task/index.ts',
+      'file:///var/task/index.tsx',
+      'file:///var/task/Index.JS',
+      'file:///var/task/index.js?v=abc123',
+      'file:///var/task/index.js#hash',
+      'file:///var/task/Component.vue',
+      'file:///var/task/page.mdx',
+    ])('reads source file %s', async filename => {
+      expect.assertions(1);
+      const frames: StackFrame[] = [{ colno: 1, filename, lineno: 1, function: 'fxn1' }];
+
+      const readStreamSpy = vi.spyOn(fs, 'createReadStream');
+      await addContext(frames);
+      expect(readStreamSpy).toHaveBeenCalledTimes(1);
+    });
+  });
+
   describe('lru file cache', () => {
     test('parseStack when file does not exist', async () => {
       expect.assertions(4);