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EUVD-2026-91564

European Vulnerability Database identifier assigned by ENISA

Reserved

2026-10-03 10:55

Assigner

ENISA

Alias of

a CVE record, shown under related vulnerabilities. This identifier carries no description, severity or references of its own: they belong to that CVE.

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{
  "assigner": "ENISA",
  "date_reserved": "2026-10-03T10:55:40.239821+00:00",
  "id": "EUVD-2026-91564"
}

CVE-2026-5947 (GCVE-0-2026-5947)

Vulnerability from cvelistv5 – Published: 2026-05-20 13:10 – Updated: 2026-09-01 12:05

Title

SIG(0) validation during query flood may lead to undefined behavior

Summary

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.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-20 13:39 UTC

CWE

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-416 - Use After Free
CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition

Assigner

isc mitre root

References

7 references

URL	Tags
https://kb.isc.org/docs/cve-2026-5947	vendor-advisory
https://downloads.isc.org/isc/bind9/9.20.23	patch
https://downloads.isc.org/isc/bind9/9.21.22	patch
https://access.redhat.com/security/cve/CVE-2026-5947	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2479772	issue-trackingx_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/v…	x_sadp-csaf-vex
https://access.redhat.com/errata/RHSA-2026:7412	vendor-advisoryx_refsource_REDHAT

Impacted products

8 products

Vendor	Product	Version
ISC	BIND 9	Affected: 9.20.0 , ≤ 9.20.22 (custom) Affected: 9.21.0 , ≤ 9.21.21 (custom) Affected: 9.20.9-S1 , ≤ 9.20.22-S1 (custom) Unaffected: 9.18.28 , ≤ 9.18.49 (custom) Unaffected: 9.18.28-S1 , ≤ 9.18.49-S1 (custom) cpe:2.3:a:isc:bind:::::::: cpe:2.3:a:isc:bind:::::::: cpe:2.3:a:isc:bind::::::::
Red Hat	Red Hat Hardened Images	Unaffected: 9.18.48-1.1.hum1 , < * (rpm) cpe:/a:redhat:hummingbird:1
Red Hat	Red Hat Enterprise Linux 10	cpe:/o:redhat:enterprise_linux:10
Red Hat	Red Hat Enterprise Linux 6	cpe:/o:redhat:enterprise_linux:6
Red Hat	Red Hat Enterprise Linux 7	cpe:/o:redhat:enterprise_linux:7
Red Hat	Red Hat Enterprise Linux 8	cpe:/o:redhat:enterprise_linux:8
Red Hat	Red Hat Enterprise Linux 9	cpe:/o:redhat:enterprise_linux:9
Red Hat	Red Hat OpenShift Container Platform 4	cpe:/a:redhat:openshift:4

Date Public

2026-05-20 00:00

Credits

ISC would like to thank Naoki Wakamatsu for bringing this vulnerability to our attention.

Show details on NVD website

JSON

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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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EUVD-2026-91564

CVE-2026-5947 (GCVE-0-2026-5947)

Tags

Sightings

Nomenclature

Related by attack behaviour