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

Vulnerability from cvelistv5 – Published: 2026-05-20 13:10 – Updated: 2026-06-30 12:11
VLAI
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 (v2.0.3)
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
References
Impacted 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)
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Red Hat Red Hat Hardened Images     cpe:/a:redhat:hummingbird:1
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Red Hat Red Hat Enterprise Linux 10     cpe:/o:redhat:enterprise_linux:10
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Red Hat Red Hat Enterprise Linux 6     cpe:/o:redhat:enterprise_linux:6
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Red Hat Red Hat Enterprise Linux 7     cpe:/o:redhat:enterprise_linux:7
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Red Hat Red Hat Enterprise Linux 8     cpe:/o:redhat:enterprise_linux:8
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Red Hat Red Hat Enterprise Linux 9     cpe:/o:redhat:enterprise_linux:9
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Red Hat Red Hat OpenShift Container Platform 4     cpe:/a:redhat:openshift:4
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Date Public
2026-05-20 00:00
Credits
ISC would like to thank Naoki Wakamatsu for bringing this vulnerability to our attention.
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}


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Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.