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CVE Record

CVE-2016-9778: An error handling certain queries using the nxdomain-redirect feature could cause a REQUIRE assertion failure in db.c

An error in handling certain queries can cause an assertion failure when a server is using the nxdomain-redirect feature to cover a zone for which it is also providing authoritative service. A vulnerable server could be intentionally stopped by an attacker if it was using a configuration that met the criteria for the vulnerability and if the attacker could cause it to accept a query that possessed the required attributes. Please note: This vulnerability affects the "nxdomain-redirect" feature, which is one of two methods of handling NXDOMAIN redirection, and is only available in certain versions of BIND. Redirection using zones of type "redirect" is not affected by this vulnerability. Affects BIND 9.9.8-S1 -> 9.9.8-S3, 9.9.9-S1 -> 9.9.9-S6, 9.11.0-9.11.0-P1.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This flaw can let a remote attacker crash a narrowly configured BIND DNS server. It matters when the server uses the nxdomain-redirect feature and also serves authority for the covered zone. The impact is availability only, but DNS outages can disrupt customer access, internal name resolution, and dependent services.

Executive priority

Prioritize remediation for internet-facing or business-critical DNS servers matching the affected versions and configuration. This is not a broad BIND emergency, but a crashable DNS service can become an operational outage if the vulnerable feature is in use.

Technical view

CVE-2016-9778 is a BIND 9 assertion failure in db.c triggered by certain queries under nxdomain-redirect. Affected versions are 9.9.8-S1 through 9.9.8-S3, 9.9.9-S1 through 9.9.9-S6, and 9.11.0 through 9.11.0-P1. Redirect zones of type redirect are stated as unaffected.

Likely exposure

Exposure is limited to BIND servers on affected versions that accept relevant DNS queries and use nxdomain-redirect while also providing authoritative service for the covered zone. General BIND deployments without this feature or using redirect zones are not identified as affected by the source bundle.

Exploitation context

The source bundle supports remote, unauthenticated denial of service under specific configuration conditions. It does not provide evidence of active exploitation, and KEV status is false. The vulnerability is easier to trigger than to broadly exploit because the target configuration is constrained.

Researcher notes

The key research condition is the intersection of affected BIND versions, nxdomain-redirect use, and authoritative service for the covered zone. The stated security impact is availability loss from a REQUIRE assertion failure. The bundle does not name confidentiality or integrity effects.

Mitigation direction

  • Inventory BIND versions against the affected release ranges.
  • Review whether nxdomain-redirect is enabled on authoritative DNS servers.
  • Apply ISC or operating-system vendor updates from the relevant advisory.
  • If patching is delayed, check vendor guidance on disabling or reconfiguring nxdomain-redirect.
  • Confirm redirect zones of type redirect are not mistakenly treated as affected.

Validation and detection

  • Verify no production server runs the listed affected BIND versions.
  • Check DNS configuration for nxdomain-redirect covering authoritative zones.
  • Review DNS service logs for assertion failures or unexplained named restarts.
  • Confirm patched packages or upgraded BIND builds are deployed.
  • Test business-critical DNS availability after remediation.
Prepared
Confidence
high
Sources
5

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.

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CVE-2016-9778 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.0)
Known Exploited
No
Published

Vector: CVSS:3.0/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.

1CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS vector scores

1 official score

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 3.0HighCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.0 score

7.5High
CVSS 3.0 vector shape for CVE-2016-9778Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.0/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

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
ISCBIND 9BIND 9 9.9.8-S1 -> 9.9.8-S3, 9.9.9-S1 -> 9.9.9-S6, 9.11.0-9.11.0-P1Listed
Weakness

CWE details

No CWE listed

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