CVE-2015-7547: Buffer Overflow
A stack-based buffer overflow was found in libresolv when invoked from nssdns, allowing specially crafted DNS responses to seize control of EIP in the DNS client.
The buffer overflow occurs in the functions senddg (send datagram) and sendvc (send TCP) for the NSS module libnssdns.so.2 when calling getaddrinfo with AFUNSPEC family, or in some cases AFINET6 family. The use of AFUNSPEC (or AFINET6 in some cases) triggers the low-level resolver code to send out two parallel queries for A and AAAA. A mismanagement of the buffers used for those queries could result in the response of a query writing beyond the alloca allocated buffer created by resnquery.
Other sources
Multiple stack-based buffer overflows in the (1) senddg and (2) sendvc functions in the libresolv library in the GNU C Library (aka glibc or libc6) before 2.23 allow remote attackers to cause a denial of service (crash) or possibly execute arbitrary code via a crafted DNS response that triggers a call to the getaddrinfo function with the AFUNSPEC or AFINET6 address family, related to performing "dual A/AAAA DNS queries" and the libnssdns.so.2 NSS module.
— MITRE
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2015-7547?
CVE-2015-7547 has a critical severity level due to its potential for remote code execution via specially crafted DNS responses.
How do I fix CVE-2015-7547?
To fix CVE-2015-7547, update the affected software packages to the patched versions provided by the software maintainers.
Which systems are affected by CVE-2015-7547?
CVE-2015-7547 affects various systems including Debian 8.0, Ubuntu 12.04, 14.04, 15.10, and several versions of HP Helion OpenStack, SUSE Linux, and Red Hat Enterprise Linux.
What types of attacks can exploit CVE-2015-7547?
CVE-2015-7547 can be exploited through remote attacks where specially crafted DNS responses can lead to stack-based buffer overflow.
What should I do if I cannot update my software to mitigate CVE-2015-7547?
If you cannot update your software, consider implementing strict egress filtering and monitoring DNS traffic to reduce the risk of exploitation from CVE-2015-7547.