Description (CNA)
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 (CNA)
| Vendor / product | Versions |
|---|---|
| ISC / BIND 9 | affected 9.20.0 through 9.20.22; affected 9.21.0 through 9.21.21; affected 9.20.9-S1 through 9.20.22-S1; unaffected 9.18.28 through 9.18.49; unaffected 9.18.28-S1 through 9.18.49-S1 |
CWE
CWE-362, CWE-416
References
- https://kb.isc.org/docs/cve-2026-5947
- https://downloads.isc.org/isc/bind9/9.20.23
- https://downloads.isc.org/isc/bind9/9.21.22
ADP enrichment
No English description supplied.
No references supplied.
A flaw was found in BIND. A remote attacker could exploit a race condition during SIG(0) signature validation of an incoming DNS message. If the "recursive-clients" limit is reached and the message is discarded, a use-after-free vulnerability may occur. This could lead to undefined behavior and potentially result in a denial of service.