Security restrictions bypass in Exim



| Updated: 2024-08-02
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2024-39929
CWE-ID CWE-20
Exploitation vector Network
Public exploit Public exploit code for vulnerability #1 is available.
Vulnerable software
 Exim
Server applications / Mail servers

Vendor Exim

Security Bulletin

This security bulletin contains one medium risk vulnerability.

1) Input validation error

EUVDB-ID: #VU94107

Risk: Medium

CVSSv4.0: 5.5 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2024-39929

CWE-ID: CWE-20 - Improper input validation

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to insufficient validation of RFC 2231 header filename. A remote attacker can bypass a $mime_filename extension-blocking protection mechanism and deliver malicious executable files to the mailboxes.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Exim: 4.00 - 4.97.1

CPE2.3 External links

https://git.exim.org/exim.git/commit/6ce5c70cff8989418e05d01fd2a57703007a6357
https://git.exim.org/exim.git/commit/1b3209b0577a9327ebb076f3b32b8a159c253f7b
https://github.com/Exim/exim/compare/exim-4.98-RC2...exim-4.98-RC3
https://www.rfc-editor.org/rfc/rfc2231.txt
https://bugs.exim.org/show_bug.cgi?id=3099#c4


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.



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