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CVE-2026-5946— Invalid handling of CLASS != IN

Quick assessment

Affected
ISC BIND 9
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

ISC BIND 9是ISC组织的一个域名系统软件。 ISC BIND 9存在输入验证错误漏洞，该漏洞源于处理非Internet类DNS消息时存在缺陷，可能导致断言失败。以下版本受到影响：9.11.0版本至9.16.50版本、9.18.0版本至9.18.48版本、9.20.0版本至9.20.22版本、9.21.0版本至9.21.21版本、9.11.3-S1版本至9.16.50-S1版本、9.18.11-S1版本至9.18.48-S1版本和9.20.9-S1版本至9.20.22-S1版本。

CVSS 7.5 · High EPSS 1.70% · P76

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 7

VendorProduct Version RangeStatus
ISC BIND 9 9.11.0≤ 9.16.50 affected
9.18.0≤ 9.18.48 affected
9.20.0≤ 9.20.22 affected
9.21.0≤ 9.21.21 affected
9.11.3-S1≤ 9.16.50-S1 affected
9.18.11-S1≤ 9.18.48-S1 affected
9.20.9-S1≤ 9.20.22-S1 affected
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I. Basic Information for CVE-2026-5946

Vulnerability Information
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Vulnerability Title
Invalid handling of CLASS != IN
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
ISC BIND 9 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
ISC BIND 9是ISC组织的一个域名系统软件。 ISC BIND 9存在输入验证错误漏洞，该漏洞源于处理非Internet类DNS消息时存在缺陷，可能导致断言失败。以下版本受到影响：9.11.0版本至9.16.50版本、9.18.0版本至9.18.48版本、9.20.0版本至9.20.22版本、9.21.0版本至9.21.21版本、9.11.3-S1版本至9.16.50-S1版本、9.18.11-S1版本至9.18.48-S1版本和9.20.9-S1版本至9.20.22-S1版本。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
ISC BIND 9 9.11.0 ~ 9.16.50 -

II. Public POCs for CVE-2026-5946

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III. Intelligence Information for CVE-2026-5946

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Patches & Fixes for CVE-2026-5946 (1)

Vendor Advisories for CVE-2026-5946 (1)

Vendor Pages for CVE-2026-5946 (2)

Same Patch Batch · ISC · 2026-05-20 · 6 CVEs total

CVE-2026-3039 7.5 HIGH BIND 9 server memory exhaustion during GSS-API TKEY negotiation
CVE-2026-5947 7.5 HIGH SIG(0) validation during query flood may lead to undefined behavior
CVE-2026-3593 7.4 HIGH Heap use-after-free vulnerability in BIND 9 DNS-over-HTTPS implementation
CVE-2026-3592 5.3 MEDIUM Amplification vulnerabilities via self-pointed glue records
CVE-2026-5950 5.3 MEDIUM Unbounded resend loop in BIND 9 resolver

IV. Related Vulnerabilities

Same product: BIND 9
Same vendor: ISC
Same weakness: CWE-20

V. Comments for CVE-2026-5946

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