CVE-2026-5947

The record

Undefined behavior may result due to a race condition leading to a use-after-free violation. If BIND receives an incoming DNS message signed with SIG(0), it begins work to validate that signature. If, during that validation, the "recursive-clients" limit is reached (as would occur during a query flood), and that same DNS message is discarded per the limit, there is a brief window of time while the SIG(0) validation may attempt to read the now-discarded DNS message. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.28 through 9.18.49 and 9.18.28-S1 through 9.18.49-S1 are NOT affected.

Affected packages

Related vulnerabilities

• CVE-2026-5950 An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during… Also affects bind
• CVE-2026-5946 Multiple flaws have been identified in `named` related to the handling of DNS messages… Also affects bind
• CVE-2026-3039 BIND servers that are configured to use TKEY-based authentication via GSS-API tokens are… Also affects bind
• CVE-2026-3592 BIND resolvers are vulnerable to an amplified resource consumption/exhaustion attack. Also affects bind
• CVE-2026-3593 A use-after-free vulnerability exists within the DNS-over-HTTPS implementation. Also affects bind
• CVE-2026-3119 Under certain conditions, `named` may crash when processing a correctly signed query… Also affects bind
• CVE-2026-3591 A use-after-return vulnerability exists in the `named` server when handling DNS queries… Also affects bind
• CVE-2026-3104 A specially crafted domain can be used to cause a memory leak in a BIND resolver simply… Also affects bind