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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.

PUBLISHED Reserved 2026-01-28 | Published 2026-03-25 | Updated 2026-04-13 | Assigner isc




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-606 Unchecked Input for Loop Condition

Product status

Default status
unaffected

9.11.0 (custom)
affected

9.18.0 (custom)
affected

9.20.0 (custom)
affected

9.21.0 (custom)
affected

9.11.3-S1 (custom)
affected

9.18.11-S1 (custom)
affected

9.20.9-S1 (custom)
affected

Credits

ISC would like to thank Samy Medjahed/Ap4sh for bringing this vulnerability to our attention.

References

lists.debian.org/debian-lts-announce/2026/04/msg00008.html

kb.isc.org/docs/cve-2026-1519 (CVE-2026-1519) vendor-advisory

downloads.isc.org/isc/bind9/9.18.47 patch

downloads.isc.org/isc/bind9/9.20.21 patch

downloads.isc.org/isc/bind9/9.21.20 patch

cve.org (CVE-2026-1519)

nvd.nist.gov (CVE-2026-1519)

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