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CVE Record

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.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-1519 can make vulnerable BIND DNS resolvers spend excessive CPU while validating DNSSEC data from a maliciously crafted zone. The main business risk is DNS service degradation or outage, not data theft. Authoritative-only BIND servers are generally less exposed unless they also make recursive queries.

Executive priority

Treat this as a high-priority DNS availability issue. Patch exposed validating resolvers promptly, especially where DNS outages would disrupt authentication, customer access, email, or production service discovery.

Technical view

Affected BIND 9 DNSSEC-validating resolvers mishandle excessive NSEC3 iteration work during insecure delegation validation, allowing unauthenticated network-triggered CPU exhaustion. The CVSS vector is AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. ISC lists fixed release branches including 9.18.47, 9.20.21, and 9.21.20.

Likely exposure

Organizations running BIND 9 recursive or caching resolvers with DNSSEC validation enabled are the primary exposure. Affected ranges include 9.11.0-9.16.50, 9.18.0-9.18.46, 9.20.0-9.20.20, 9.21.0-9.21.19, and listed Subscription Edition ranges.

Exploitation context

The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The vulnerability is still operationally important because it is network reachable, requires no authentication or user interaction, and targets availability of DNS resolution.

Researcher notes

Evidence supports denial-of-service impact through excessive CPU consumption during DNSSEC NSEC3 processing. CWE mappings are CWE-606 and CWE-770. Do not assume confidentiality or integrity impact from the supplied sources. Patch status is supported by ISC fixed-release references and downstream vendor advisories.

Mitigation direction

  • Upgrade BIND to an ISC fixed release or vendor-patched package.
  • Prioritize internet-facing recursive resolvers and shared DNS infrastructure.
  • Review authoritative-only servers for unexpected recursive query behavior.
  • Follow Debian, Red Hat, or other distribution guidance where packaged BIND is used.
  • Monitor resolver CPU, DNSSEC validation failures, and service saturation after remediation.

Validation and detection

  • Inventory BIND versions across recursive, caching, and authoritative DNS servers.
  • Confirm DNSSEC validation is enabled on each recursive resolver.
  • Verify versions are outside affected ranges or match vendor-fixed builds.
  • Check authoritative servers do not permit unintended recursion.
  • Review applicable ISC and OS vendor advisories for package-specific status.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-606: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-770: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-1519 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
3ADP providers
29Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6isc
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-1519Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container
redhat-SADPbind: BIND: Denial of Service via maliciously crafted DNSSEC-validated zone
other:Red Hat severity ratingcvssV3_1
  • 2026-03-25T14:01:56.586Z: Reported to Red Hat.
  • 2026-03-25T13:25:19.802Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
ISCBIND 99.11.0, 9.18.0, 9.20.0, 9.21.0, 9.11.3-S1, 9.18.11-S1, 9.20.9-S1unaffected
Weakness

CWE details

CWE-606CWE-770

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-606 · source CWE mapping

Unchecked Input for Loop Condition

Unchecked Input for Loop Condition represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-770 · source CWE mapping

Allocation of Resources Without Limits or Throttling

Allocation of Resources Without Limits or Throttling represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs