CVE-2022-41725 Excessive resource consumption in mime/multipart

High 7.5 Published 28 Feb 2023 Updated 7 Mar 2025

Attackers can cause denial of service via excessive memory and disk consumption in Go's multipart form parsing.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2022-41725?

CVE-2022-41725 is a high-severity denial of service vulnerability in Golang Go, published on 28 Feb 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A denial of service is possible from excessive resource consumption in net/http and mime/multipart. Multipart form parsing with mime/multipart.Reader.ReadForm can consume largely unlimited amounts of memory and disk files. This also affects form parsing in the net/http package with the Request methods FormFile, FormValue, ParseMultipartForm, and PostFormValue. ReadForm takes a maxMemory parameter, and is documented as storing "up to maxMemory bytes +10MB (reserved for non-file parts) in memory". File parts which cannot be stored in memory are stored on disk in temporary files. The unconfigurable 10MB reserved for non-file parts is excessively large and can potentially open a denial of service vector on its own. However, ReadForm did not properly account for all memory consumed by a parsed form, such as map entry overhead, part names, and MIME headers, permitting a maliciously crafted form to consume well over 10MB. In addition, ReadForm contained no limit on the number of disk files created, permitting a relatively small request body to create a large number of disk temporary files. With fix, ReadForm now properly accounts for various forms of memory overhead, and should now stay within its documented limit of 10MB + maxMemory bytes of memory consumption. Users should still be aware that this limit is high and may still be hazardous. In addition, ReadForm now creates at most one on-disk temporary file, combining multiple form parts into a single temporary file. The mime/multipart.File interface type's documentation states, "If stored on disk, the File's underlying concrete type will be an *os.File.". This is no longer the case when a form contains more than one file part, due to this coalescing of parts into a single file. The previous behavior of using distinct files for each form part may be reenabled with the environment variable GODEBUG=multipartfiles=distinct. Users should be aware that multipart.ReadForm and the http.Request methods that call it do not limit the amount of disk consumed by temporary files. Callers can limit the size of form data with http.MaxBytesReader.

Weakness: CWE-770

Which versions are affected by CVE-2022-41725?

2 open source packages ship an affected version, including golang and stdlib. It affects 1 product.

Package	Affected	Fixed in
`golang` Bitnami	All versions	`1.19.6, 1.20.1`
`stdlib` Go	All versions	`1.19.6, 1.20.1`

Products include Golang Go.

How do I fix CVE-2022-41725?

Upgrade golang to a fixed version for your release line: 1.19.6 or 1.20.1.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2022-41725 being exploited?

There is no known exploitation of CVE-2022-41725 in the wild and no public exploit code.

All Golang Go vulnerabilities

Sources

Also known as AZL-13732, AZL-13739, AZL-34761, AZL-37334, AZL-37487, AZL-78992 and 7 more.