CVE-2026-5946 Isc — Exploit & Vulnerability Details HIGH

Parameter	Value
CVSS	7.5 (HIGH)
Affected Versions	9.11.0 — 9.21.22
Fixed In	9.18.49
Type	CWE-617, CWE-20 (Improper Input Validation), CWE-754, CWE-843 (Type Confusion), CWE-1287, CWE-125 (Out-of-bounds Read)
Vendor	Isc
Public PoC	No

Multiple flaws have been identified in `named` related to the handling of DNS messages whose CLASS is not Internet (`IN`) — for example, `CHAOS` or `HESIOD`, or DNS messages that specify meta-classes (`ANY` or `NONE`) in the question section. Specially crafted requests reaching the affected code paths — recursion, dynamic updates (`UPDATE`), zone change notifications (`NOTIFY`), or processing of `IN`-specific record types in non-`IN` data — can cause assertion failures in `named`. This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

Attack Parameters

Attack Vector

Network

Can be exploited remotely

Attack Complexity

Low

Easy to exploit

Privileges Required

None

No privileges needed

User Interaction

None

No user interaction needed

Impact Assessment

Confidentiality

None

No data leak

Integrity

None

No data modification

Availability

High

Complete denial of service

CVSS Vector v3.1

Weakness Type (CWE)

CWE-617

CWE-20 Improper Input Validation

CWE-754

CWE-843 Type Confusion

CWE-1287

CWE-125 Out-of-bounds Read

Vulnerable Products 11

Configuration	From (including)	Up to (excluding)
Isc Bind cpe:2.3:a:isc:bind:::::-:::*	`9.11.0`	`<= 9.16.50`
Isc Bind cpe:2.3:a:isc:bind:::::-:::*	`9.18.0`	`9.18.49`
Isc Bind cpe:2.3:a:isc:bind:::::-:::*	`9.20.0`	`9.20.23`
Isc Bind cpe:2.3:a:isc:bind:::::-:::*	`9.21.0`	`9.21.22`
Isc Bind cpe:2.3:a:isc:bind::::::::	`9.11.0`	`<= 9.16.50`
Isc Bind cpe:2.3:a:isc:bind::::::::	`9.18.0`	`<= 9.18.48`
Isc Bind cpe:2.3:a:isc:bind::::::::	`9.20.0`	`<= 9.20.22`
Isc Bind cpe:2.3:a:isc:bind::::::::	`9.21.0`	`<= 9.21.21`
Isc Bind cpe:2.3:a:isc:bind::::::::	`9.11.3-S1`	`<= 9.16.50-S1`
Isc Bind cpe:2.3:a:isc:bind::::::::	`9.18.11-S1`	`<= 9.18.48-S1`
Isc Bind cpe:2.3:a:isc:bind::::::::	`9.20.9-S1`	`<= 9.20.22-S1`