Use-After-Free Vulnerability in BIND 9 Resolver by ISC
CVE-2026-19662

5.9MEDIUM

Key Information:

Vendor

Isc
Status
Bind 9
Vendor
CVE Published:
16 September 2026

Badges

👾 Exploit Exists

What is CVE-2026-19662?

A use-after-free vulnerability exists in the BIND 9 DNS resolver that can be exploited by an attacker to induce the resolver to abort. This exploitation occurs when the victim resolver is tricked into sending multiple queries for a DNSSEC-signed zone controlled by the attacker. If specific crafted answers are returned by the authoritative server in a certain order and time frame, the named resolver may experience a use-after-free condition, leading to an unexpected abort and potentially disrupting DNS services.

Affected Version(s)

BIND 9 9.11.0 <= 9.18.50

BIND 9 9.20.0 <= 9.20.27

BIND 9 9.11.3-S1 <= 9.18.50-S1

References

https://kb.isc.org/docs/cve-2026-19662
vendor-advisory
https://downloads.isc.org/isc/bind9/9.20.29
patch

CVSS V3.1

Score:
5.9
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

ISC would like to thank Samy Medjahed/Ap4sh for bringing this vulnerability to our attention.
.