#VU66692 Release of invalid pointer or reference in Exim - CVE-2022-37451

Vulnerability identifier: #VU66692

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2022-37451

CWE-ID: CWE-763

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Exim
Server applications / Mail servers

Vendor: Exim

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to an invalid free in pam_converse() function in auths/call_pam.c. A remote attacker can initiate the connection to the affected mail server and perform a denial of service (DoS) attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Exim: 4.00 - 4.95

---

External links
https://www.exim.org/static/doc/security/
https://github.com/ivd38/exim_invalid_free
https://github.com/Exim/exim/compare/exim-4.95...exim-4.96
https://lists.exim.org/lurker/message/20220625.141825.d6de6074.en.html
https://www.openwall.com/lists/oss-security/2022/08/06/1
https://github.com/Exim/exim/wiki/EximSecurity
https://cwe.mitre.org/data/definitions/762.html
https://github.com/Exim/exim/commit/51be321b27825c01829dffd90f11bfff256f7e42

---

Q & A

Can this vulnerability be exploited remotely?

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

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.