CyberSecBulletin
CVE-2026-1519NVD status: Modified

BIND 9: Unchecked Input for Loop Condition

Published Updated By the CyberSecBulletin desk

CVE-2026-1519 is a high-severity unchecked input for loop condition vulnerability in BIND 9 from ISC, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected BIND 9 versions: 9.11.0 through 9.16.50; 9.18.0 through 9.18.46; 9.20.0 through 9.20.20, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.72% chance of exploitation within 30 days, higher than 78% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Bind to 9.18.47 or 9.20.21 or 9.21.20, whichever matches your release line, or a later version.
  2. Read the advisory on kb.isc.org for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
ISCBIND 99.11.0 through 9.16.50; 9.18.0 through 9.18.46; 9.20.0 through 9.20.20; 9.21.0 through 9.21.19; 9.11.3-S1 through 9.16.50-S1; 9.18.11-S1 through 9.18.46-S1; 9.20.9-S1 through 9.20.20-S1Not stated
Red HatRed Hat Enterprise Linux 10Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 10.0 Extended Update SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSIONNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 7 Extended Lifecycle SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-OnNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.6 Telecommunications Update ServiceNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.6 Update Services for SAP SolutionsNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update ServiceNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP SolutionsNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP SolutionsNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.4 Update Services for SAP SolutionsNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.6 Extended Update SupportNot specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.12Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.13Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.14Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.15Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.16Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.17Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.19Not specified in the recordNot stated

Version data comes from the organisation that assigned the CVE; 3 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (isc.org).

Scoring systemScoreSeverityScored by
CVSS 3.17.5HighCNA (isc.org)
CVSS 3.17.5HighCNA

Official description

If a BIND resolver is performing DNSSEC validation and encounters a maliciously crafted zone, the resolver may consume excessive CPU. Authoritative-only servers are generally unaffected, although there are circumstances where authoritative servers may make recursive queries (see: https://kb.isc.org/docs/why-does-my-authoritative-server-make-recursive-queries). This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.46, 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.46-S1, and 9.20.9-S1 through 9.20.20-S1.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Unchecked Input for Loop Condition

The product does not properly check inputs that are used for loop conditions, potentially leading to a denial of service or other consequences because of excessive looping.

How developers prevent this class of flaw

  • Do not use user-controlled data for loop conditions.

More Unchecked Input for Loop Condition vulnerabilities (CWE-606)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in BIND 9

All BIND 9 vulnerabilities

Recent Unchecked Input for Loop Condition vulnerabilities

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