CVE-2026-5947— SIG(0) validation during query flood may lead to undefined behavior
Possible ATT&CK Techniques 1AI
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I. Basic Information for CVE-2026-5947
Vulnerability Information
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Vulnerability Title
SIG(0) validation during query flood may lead to undefined behavior
Source: NVD (National Vulnerability Database)
Vulnerability Description
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.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: NVD (National Vulnerability Database)
Vulnerability Type
使用共享资源的并发执行不恰当同步问题(竞争条件)
Source: NVD (National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-5947
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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-2026-5946 | 7.5 HIGH | Invalid handling of CLASS != IN |
| 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
- CVE-2026-5950
Unbounded resend loop in BIND 9 resolver - CVE-2026-5946
Invalid handling of CLASS != IN - CVE-2026-3593
Heap use-after-free vulnerability in BIND 9 DNS-over-HTTPS i - CVE-2026-3592
Amplification vulnerabilities via self-pointed glue records - CVE-2026-3039
BIND 9 server memory exhaustion during GSS-API TKEY negotiat
Same vendor: ISC
- CVE-2026-5950
Unbounded resend loop in BIND 9 resolver - CVE-2026-5946
Invalid handling of CLASS != IN - CVE-2026-3593
Heap use-after-free vulnerability in BIND 9 DNS-over-HTTPS i - CVE-2026-3592
Amplification vulnerabilities via self-pointed glue records - CVE-2026-3039
BIND 9 server memory exhaustion during GSS-API TKEY negotiat
V. Comments for CVE-2026-5947
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