GO-2024-2963 BIT-golang-2024-24791 CVE-2024-24791

Denial of service due to improper 100-continue handling in net/http

High Go

Severity: 7.5 / 10; High · CVSS 3.1
Exploit chance (EPSS): 1.41%; Chance of exploitation in the next 30 days. Higher than 72.74% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: —; Not classified
Fix: 1.22.5; Upgrade stdlib to this version or later

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.

Affected versions

Go

Package	Vulnerable	Fixed in
stdlib	`< 1.21.12` `>= 1.22.0-0, < 1.22.5`	`1.21.12` `1.22.5`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

stdlib Go → `1.22.5`

go

go get stdlib@v1.22.5 && go mod tidy

Severity breakdown

CVSS 3.1 7.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

References

Fixes and patches

go.dev/cl/591255

Issue reports

go.dev/issue/67555

Timeline

Jul 2, 2024 Published
Jun 17, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-4374-p667-p6c8 HTTP/2 rapid reset can cause excessive work in net/http	High Known exploited	Also affects stdlib
CVE-2020-0601 Certificate validation bypass on Windows in crypto/x509	High Known exploited	Also affects stdlib
RUSTSEC-2026-0382 Distrust compromised intermediate certificates in crypto/x509	Medium	Also affects stdlib
GO-2026-6613 HTTP/1 server connection desynchronization after 2xx CONNECT response in net/http	High	Also affects stdlib
GO-2026-6609 Lack of limit on size of parsed Range headers in net/http	High	Also affects stdlib
GO-2026-6608 Memory limit bypass when parsing MIME headers in net/textproto, mime/multipart	High	Also affects stdlib
GO-2026-6607 Reject malformed ECH outer extension references in crypto/tls	High	Also affects stdlib
GO-2026-6604 Root.Mkdir(All) can follow junctions out of the root on Windows in os	Critical	Also affects stdlib

Credits: Geoff Franks

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