Exim dkim_exim_query_dns_txt() buffer overflow

exim-dkimeximquerydnstxt-bo (79615) The risk level is classified as HighHigh Risk

Description:

EXIM is vulnerable to a heap-based buffer overflow, caused by improper bounds checking by the dkim_exim_query_dns_txt() function when processing a DNS record. If the application is built with DKIM support, a remote attacker could use an email from a domain where the attacker controls DNS to overflow a buffer and execute arbitrary code on the system or cause the application to crash.

*CVSS:

Base Score: 7.5
  Access Vector: Network
  Access Complexity: Low
  Authentication: None
  Confidentiality Impact: Partial
  Integrity Impact: Partial
  Availability Impact: Partial
 
Temporal Score: 5.5
  Exploitability: Unproven
  Remediation Level: Official-Fix
  Report Confidence: Confirmed

Consequences:

Gain Access

Remedy:

Upgrade to the latest version of Exim (4.80.1 or later), available from the Exim Web site. See References.

For other distributions:
Apply the appropriate update for your system. See References.

References:

  • Exim Web site: Exim 4.80.1 Security Release.
  • Sophos Web site: Sophos UTM.
  • BID-56285: Exim DKIM DNS Decoding CVE-2012-5671 Remote Buffer Overflow Vulnerability
  • CVE-2012-5671: Heap-based buffer overflow in the dkim_exim_query_dns_txt function in dkim.c in Exim 4.70 through 4.80, when DKIM support is enabled and acl_smtp_connect and acl_smtp_rcpt are not set to warn control = dkim_disable_verify
  • DSA-2566: exim4 -- heap-based buffer overflow
  • OSVDB ID: 86616: Exim src/dkim.c dkim_exim_query_dns_txt() Function DNS Record Parsing Remote Overflow
  • SA51098: Exim DKIM DNS Decoding Buffer Overflow Vulnerability
  • SA51339: Sophos UTM Cross-Site Scripting and Buffer Overflow Vulnerabilities

Platforms Affected:

  • Exim Exim 4.70
  • Exim Exim 4.71
  • Exim Exim 4.72
  • Exim Exim 4.75
  • Exim Exim 4.80
  • Sophos Sophos UTM 9.000

Reported:

Oct 26, 2012

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The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall IBM be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.

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