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CVE-2026-1519

Excessive NSEC3 iterations cause high CPU load during insecure delegation validation

Published: Mar 25, 2026Updated: May 21, 2026 Sources: CVE List NVDCWE-606
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.8%
Top 47.5%
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-606

Affected Products

BIND 9ISCNetworking Infrastructure
bindiscNetworking Infrastructure
isccommercialUSNetworking Infrastructureaka internet systems consortium

Exploitability

0 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available
Workaround Available

References

https://kb.isc.org/docs/cve-2026-1519
kb.isc.org
https://downloads.isc.org/isc/bind9/9.18.47
downloads.isc.org
https://downloads.isc.org/isc/bind9/9.20.21
downloads.isc.org
and 2 more references View all →

Timeline

Published
Mar 25, 2026
Last Updated
May 21, 2026

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