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CVE-2026-5950 (GCVE-0-2026-5950)

Vulnerability from cvelistv5 – Published: 2026-05-20 13:10 – Updated: 2026-05-20 13:38
VLAI
Title
Unbounded resend loop in BIND 9 resolver
Summary
An unbounded resend loop vulnerability exists in the BIND 9 resolver state machine during bad-server handling, enabling a remote unauthenticated attacker to cause severe resource exhaustion by sending queries that trigger specific retry conditions. This issue affects BIND 9 versions 9.18.36 through 9.18.48, 9.20.8 through 9.20.22, 9.21.7 through 9.21.21, 9.18.36-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-05-20 13:38 UTC
CWE
  • CWE-606 - Unchecked Input for Loop Condition
Assigner
References
Impacted products
Vendor Product Version CPE status
ISC BIND 9 Affected: 9.18.36 , ≤ 9.18.48 (custom)
Affected: 9.20.8 , ≤ 9.20.22 (custom)
Affected: 9.21.7 , ≤ 9.21.21 (custom)
Affected: 9.18.36-S1 , ≤ 9.18.48-S1 (custom)
Affected: 9.20.9-S1 , ≤ 9.20.22-S1 (custom)
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
    cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
Create a notification for this product.
Date Public
2026-05-20 00:00
Credits
ISC would like to thank Billy Baraja (BielraX) for bringing this vulnerability to our attention.
Show details on NVD website
To clipboard 

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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

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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.


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