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

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.

Published: 2026-03-25 Last update: 2026-05-21 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-1519 is rated Low Risk (36.7/100): CVSS High severity, with low exploitation likelihood (EPSS 0.06%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-1519

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-01 0.04% 0.06% +0.02%
2 2026-05-29 0.07% 0.04% -0.03%
3 2026-05-23 — 0.07% —

Full EPSS history (6 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-1519

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-1519

OS Trackers for CVE-2026-1519

vendor priority summary link
alpine — CVE-2026-1519: 1 source package rows (bind); 5 state rows across 5 repos (3.20-main, 3.21-main, 3.22-main, 3.23-main, edge-main); fixed 5, open 0. https://security.alpinelinux.org/vuln/CVE-2026-1519
debian not yet assigned CVE-2026-1519 not yet assigned priority: Debian including 1 source packages (bind9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-1519
redhat high — https://access.redhat.com/security/cve/CVE-2026-1519
suse high — https://www.suse.com/security/cve/CVE-2026-1519/
ubuntu medium CVE-2026-1519 medium priority: Ubuntu including 3 source packages (bind9, bind9-libs, isc-dhcp), 21 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): needs-triage 11, not-affected 4, released 4, DNE 2. https://ubuntu.com/security/CVE-2026-1519

Affected software / configurations for CVE-2026-1519

Vendor Product Version Raw CPE
isc bind >= 9.11.0, <= 9.16.50 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.18.0, < 9.18.47 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.20.0, < 9.20.21 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.21.0, < 9.21.20 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*

References for CVE-2026-1519

cvelogic Threat Intelligence