#VU12130 Use of externally-controlled format string in Exim - CVE-2011-1764

Vulnerability identifier: #VU12130

Vulnerability risk: High

CVSSv4.0: 8.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2011-1764

CWE-ID: CWE-134

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Exim
Server applications / Mail servers

Vendor: Exim

Description
The vulnerability allows a remote attacker to cause DoS condition or execute arbitrary code on the target system.

The weakness exists in the dkim_exim_verify_finish function in src/dkim.c due to use of externally-controlled format string. A remote attacker can cause the service to crash or execute arbitrary code via format string specifiers in data used in DKIM logging, as demonstrated by an identity field containing a % (percent) character.

Successful exploitation of the vulnerability may result in system compromise.

Mitigation
Update to version 4.76.

Vulnerable software versions

Exim: 4.50 - 4.75

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External links
https://git.exim.org/exim.git/commit/337e3505b0e6cd4309db6bf6062b33fa56e06cf8

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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.