blob: 04b818595b66aec2e376c43eb09b39a5afbe6e54 [file] [log] [blame]
id: GO-2023-1569
modules:
- module: std
versions:
- fixed: 1.19.6
- introduced: 1.20.0-0
fixed: 1.20.1
vulnerable_at: 1.20.0
packages:
- package: mime/multipart
symbols:
- Reader.ReadForm
summary: Excessive resource consumption in mime/multipart
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.
credits:
- Arpad Ryszka
- Jakob Ackermann (@das7pad)
references:
- report: https://go.dev/issue/58006
- fix: https://go.dev/cl/468124
- web: https://groups.google.com/g/golang-announce/c/V0aBFqaFs_E
cve_metadata:
id: CVE-2022-41725
cwe: 'CWE-400: Uncontrolled Resource Consumption'
references:
- https://security.gentoo.org/glsa/202311-09
review_status: REVIEWED