CVE-2021-25214

In BIND 9.8.5 -> 9.8.8, 9.9.3 -> 9.11.29, 9.12.0 -> 9.16.13, and versions BIND 9.9.3-S1 -> 9.11.29-S1 and 9.16.8-S1 -> 9.16.13-S1 of BIND 9 Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.11 of the BIND 9.17 development branch, when a vulnerable version of named receives a malformed IXFR triggering the flaw described above, the named process will terminate due to a failed assertion the next time the transferred secondary zone is refreshed.

Weakness

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Affected Software

Extended Description

While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.

Potential Mitigations

References

• http://www.openwall.com/lists/oss-security/2021/04/29/1
• http://www.openwall.com/lists/oss-security/2021/04/29/2
• http://www.openwall.com/lists/oss-security/2021/04/29/3
• http://www.openwall.com/lists/oss-security/2021/04/29/4
• https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
• https://kb.isc.org/v1/docs/cve-2021-25214
• https://lists.debian.org/debian-lts-announce/2021/05/msg00001.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VEC2XG4Q2ODTN2C4CGXEIXU3EUTBMK7L/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZDSRPCJQ7MZC6CENH5PO3VQOFI7VSWBE/
• https://security.netapp.com/advisory/ntap-20210521-0006/
• https://www.debian.org/security/2021/dsa-4909