Executive brief
BIND is a widely used software suite for managing the Domain Name System (DNS), which translates human-readable web addresses into IP addresses. A vulnerability has been identified where processing a specially crafted, invalid DNS record can cause the BIND server to crash. This could lead to a denial-of-service, preventing users from accessing websites or services that rely on the affected DNS server.
Technical details
A vulnerability exists in BIND 9's handling of DNS records (such as KEY or DNSKEY) that utilize the PRIVATEDNS algorithm (253). The flaw is triggered when a record contains an algorithm identifier with a length field that exceeds the actual data provided. While BIND initially accepts and stores this malformed record, a subsequent attempt to render the record to text causes a consistency check failure (assertion failure). This results in the BIND process aborting and exiting. The issue is reachable remotely if the server is configured to process or display such records. Patches are available in versions 9.20.26 and 9.21.24.
Affected products
- ISC BIND 9 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.18.11-S1 through 9.18.50-S1, 9.20.9-S1 through 9.20.24-S1
Timeline
- 2026-07-15: other: Early notification issued
- 2026-07-22: disclosed: Public disclosure of the vulnerability
- 2026-07-22: patched: Patched versions 9.20.26 and 9.21.24 released