CVE-2026-1519: Excessive NSEC3 iterations cause high CPU load during insecure delegation validation

High severity · published Mar 25, 2026

CVE-2026-1519

Excessive NSEC3 iterations cause high CPU load during insecure delegation validation

7.5

CVSS

1.7%

EPSS

On KEV

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

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

Attack vector

Network

Complexity

Low

Privileges

None

User interaction

None

Confidentiality

None

Integrity

None

Availability

High

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)1.7% · higher than 77% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

BIND 9 · ISC

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; +1 more · source: vendor

Bind · Isc

9.11.0 through 9.16.50; 9.18.0 before 9.18.47; 9.20.0 before 9.20.21; 9.21.0 before 9.21.20 · source: NVD

Red Hat Enterprise Linux 10 · Red Hat