CVE-2024-22049

httparty has multipart/form-data request tampering vulnerability

I found "multipart/form-data request tampering vulnerability" caused by Content-Disposition "filename" lack of escaping in httparty.

httparty/lib/httparty/request > body.rb > def generate_multipart

https://github.com/jnunemaker/httparty/blob/4416141d37fd71bdba4f37589ec265f55aa446ce/lib/httparty/request/body.rb#L43

By exploiting this problem, the following attacks are possible

• An attack that rewrites the "name" field according to the crafted file name, impersonating (overwriting) another field.
• Attacks that rewrite the filename extension at the time multipart/form-data is generated by tampering with the filename

For example, this vulnerability can be exploited to generate the following Content-Disposition.

Normal Request example:
normal input filename: abc.txt

generated normal header in multipart/form-data
Content-Disposition: form-data; name="avatar"; filename="abc.txt"

Malicious Request example
malicious input filename: overwrite_name_field_and_extension.sh"; name="foo"; dummy=".txt

generated malicious header in multipart/form-data:
Content-Disposition: form-data; name="avatar"; filename="overwrite_name_field_and_extension.sh"; name="foo"; dummy=".txt"

The Abused Header has multiple name ( avatar & foo ) fields and the "filename" has been rewritten from *.txt to *.sh .

These problems can result in successful or unsuccessful attacks, depending on the behavior of the parser receiving the request.
I have confirmed that the attack succeeds, at least in the following frameworks

• Spring (Java)
• Ktor (Kotlin)
• Ruby on Rails (Ruby)

The cause of this problem is the lack of escaping of the " (Double-Quote) character in Content-Disposition > filename.

WhatWG's HTML spec has an escaping requirement.

https://html.spec.whatwg.org/#multipart-form-data

For field names and filenames for file fields, the result of the encoding in the previous bullet point must be escaped by replacing any 0x0A (LF) bytes with the byte sequence %0A, 0x0D (CR) with %0D and 0x22 (") with %22. The user agent must not perform any other escapes.

CVE-2024-22049 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and user interaction required. 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 (0.21.0); upgrading removes the vulnerable code path.

Kodem intelligence

As noted at the beginning of this section, encoding must be done as described in the HTML Spec.

https://html.spec.whatwg.org/#multipart-form-data

For field names and filenames for file fields, the result of the encoding in the previous bullet point must be escaped by replacing any 0x0A (LF) bytes with the byte sequence %0A, 0x0D (CR) with %0D and 0x22 (") with %22. The user agent must not perform any other escapes.

Therefore, it is recommended that Content-Disposition be modified by either of the following

Before:
Content-Disposition: attachment;filename="malicious.sh";dummy=.txt

After:
Content-Disposition: attachment;filename="%22malicious.sh%22;dummy=.txt"

https://github.com/jnunemaker/httparty/blob/4416141d37fd71bdba4f37589ec265f55aa446ce/lib/httparty/request/body.rb#L43

file_name.gsub('"', '%22')

Also, as for \r, \n, URL Encode is not done, but it is not newlines, so it seemed to be OK.
However, since there may be omissions, it is safer to URL encode these as well, if possible.
( \r to %0A and \d to %0D )

1. What is CVE-2024-22049? CVE-2024-22049 is a medium-severity security vulnerability in httparty (rubygems), affecting versions <= 0.20.0. It is fixed in 0.21.0.
2. How severe is CVE-2024-22049? CVE-2024-22049 has a CVSS score of 6.5 (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 httparty are affected by CVE-2024-22049? httparty (rubygems) versions <= 0.20.0 is affected.
4. Is there a fix for CVE-2024-22049? Yes. CVE-2024-22049 is fixed in 0.21.0. Upgrade to this version or later.
5. Is CVE-2024-22049 exploitable, and should I be worried? Whether CVE-2024-22049 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-2024-22049 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-2024-22049? Upgrade httparty to 0.21.0 or later.