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CVE Record

CVE-2026-3104: Memory leak in code preparing DNSSEC proofs of non-existence

A specially crafted domain can be used to cause a memory leak in a BIND resolver simply by querying this domain. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A maliciously designed domain can make vulnerable BIND DNS resolvers retain memory when users or systems query it. Memory consumption may eventually disrupt DNS resolution or terminate the service, affecting applications that depend on it. The issue does not expose or alter data, but it can cause significant availability loss.

Executive priority

Treat this as a high-priority DNS availability issue. Expedite updates for exposed production resolvers because unauthenticated queries can trigger the flaw and DNS disruption can cascade across dependent services. It is not presented as a data breach or code-execution vulnerability. Confirm inventory and patch externally reachable resolvers first.

Technical view

CVE-2026-3104 is a CWE-772 resource-release flaw in code preparing DNSSEC proofs of non-existence. It is remotely triggerable without privileges or user interaction. Affected branches are 9.20.0–9.20.20, 9.21.0–9.21.19, and 9.20.9-S1–9.20.20-S1. Listed 9.18 releases are unaffected. CVSS 3.1 is 7.5, reflecting high availability impact.

Likely exposure

Exposure exists where an affected BIND installation operates as a resolver and processes queries capable of reaching attacker-controlled domains. Public recursive resolvers face the clearest risk, but restricted resolvers may also be affected if an authorized client queries the crafted domain. Authoritative-only deployments are not established as exposed by the supplied evidence.

Exploitation context

The source bundle reports no evidence of active exploitation, and the CVE is not identified as being in KEV. Exploitation requires causing a vulnerable resolver to query a specially crafted domain. The resulting memory leak creates denial-of-service potential; the sources do not claim confidentiality loss, data modification, or code execution.

Researcher notes

The supplied evidence establishes a network-triggered memory leak during DNSSEC denial-of-existence proof preparation, but does not quantify leakage per query, time to exhaustion, required query repetition, or observed attacks. Avoid production trigger testing because validation may consume memory. Use version, deployment-role, package, and operational telemetry checks instead.

Mitigation direction

  • Upgrade BIND 9.20 deployments to version 9.20.21 using ISC or supported distributor packages.
  • Upgrade BIND 9.21 deployments to version 9.21.20 using ISC or supported distributor packages.
  • For affected S1 builds, obtain the applicable fixed-release guidance directly from ISC.
  • Prioritize resolvers that accept public, untrusted, or broadly accessible client queries.

Validation and detection

  • Inventory every resolver’s exact BIND edition, branch, and installed version.
  • Identify systems within the three affected version ranges and confirm their resolver role.
  • Confirm upgraded 9.20 systems report version 9.20.21 and 9.21 systems report version 9.21.20.
  • Verify listed 9.18 installations separately and document them as unaffected by this CVE.
  • Review resolver memory, service restarts, and resource-exhaustion events for unexplained patterns.
Prepared
Confidence
high
Sources
6

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

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cwe · low confidence lookup

CWE-772: 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.

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cve · low confidence lookup

CVE-2026-3104 mapping review

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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
2ADP providers
8Source 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-2026-3104Attack 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
redhat-SADPbind: BIND: Denial of Service via specially crafted domain query causing a memory leak
other:Red Hat severity ratingcvssV3_1
  • 2026-03-25T14:02:15.067Z: Reported to Red Hat.
  • 2026-03-25T13:29:19.494Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
ISCBIND 99.20.0, 9.21.0, 9.20.9-S1, 9.18.0, 9.18.11-S1unaffected
Weakness

CWE details

CWE-772

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

CWE-772 · source CWE mapping

Missing Release of Resource after Effective Lifetime

Missing Release of Resource after Effective Lifetime represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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