--- title: "CVE-2015-8461: A race condition when handling socket errors can lead to an assertion failure in resolver.c" slug: "aa-01319" description: "Beginning with the September 2015 maintenance releases 9.9.8 and 9.10.3, an error was introduced into BIND 9 which can cause a server to exit after encountering an INSIST assertion failure in resolver.c." updated: 2018-10-31T15:27:32Z published: 2018-10-31T15:27:32Z canonical: "kb.isc.org/aa-01319" --- > ## Documentation Index > Fetch the complete documentation index at: https://kb.isc.org/llms.txt > Use this file to discover all available pages before exploring further. # CVE-2015-8461: A race condition when handling socket errors can lead to an assertion failure in resolver.c **CVE:** [CVE-2015-8461](http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-8461) **Document version:** 2.0 **Posting date:** 15 December 2015 **Program impacted:** [BIND](https://www.isc.org/downloads/bind) **Versions affected:** 9.9.8 -> 9.9.8-P1, 9.9.8-S1 -> 9.9.8-S2, 9.10.3 -> 9.10.3-P1 **Severity:** Medium **Exploitable:** Remotely **Description:** Beginning with the September 2015 maintenance releases 9.9.8 and 9.10.3, an error was introduced into BIND 9 which can cause a server to exit after encountering an INSIST assertion failure in resolver.c. **Impact:** An uncommonly occurring condition can cause affected servers to exit with an INSIST failure depending on the outcome of a race condition in resolver.c. While difficult to exploit reliably, a malicious party could, through deliberate behavior, significantly increase the probability of encountering the triggering condition, resulting in denial of service to clients if successful. **CVSS Score:** 5.4 **CVSS Vector:** (AV:N/AC:H/Au:N/C:N/I:N/A:C) For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: [https://nvd.nist.gov/cvss.cfm?calculator&version=2&vector=(AV:N/AC:H/Au:N/C:N/I:N/A:C)](https://nvd.nist.gov/cvss.cfm?calculator&version=2&vector=(AV:N/AC:H/Au:N/C:N/I:N/A:C)). **Workarounds:** None. **Active exploits:** None known. **Solution:** Upgrade to the patched release most closely related to your current version of BIND. Public open-source branches can be downloaded from [https://www.isc.org/downloads](https://www.isc.org/downloads). - BIND 9 version 9.9.8-P2 - BIND 9 version 9.10.3-P2 BIND 9 Supported Preview edition is a feature preview version of BIND provided exclusively to eligible ISC Support customers. - BIND 9 version 9.9.8-S3 **Acknowledgements:** ISC would like to thank John O'Brien of the University of Pennsylvania for discovering this issue. **Document Revision History:** 1.0 Advance Notification. 8 December 2015 2.0 Public Disclosure. 15 December 2015 **Related Documents:** See our [BIND 9 Security Vulnerability Matrix](https://kb.isc.org/docs/aa-00913) for a complete listing of Security Vulnerabilities and versions affected. 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(For current information on which versions are actively supported, please see [https://www.isc.org/downloads/](https://www.isc.org/downloads)). **ISC Security Vulnerability Disclosure Policy:** Details of our current security advisory policy and practice can be found in the [ISC Software Defect and Security Vulnerability Disclosure Policy](https://kb.isc.org/docs/aa-00861). This [Knowledgebase article](https://kb.isc.org/docs/aa-01319) is the complete and official security advisory document. **Legal Disclaimer:** Internet Systems Consortium (ISC) is providing this notice on an "AS IS" basis. No warranty or guarantee of any kind is expressed in this notice and none should be implied. ISC expressly excludes and disclaims any warranties regarding this notice or materials referred to in this notice, including, without limitation, any implied warranty of merchantability, fitness for a particular purpose, absence of hidden defects, or of non-infringement. 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