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VulnerabilityPublished Updated

CVE-2026-78301: ISC BIND 9 · Acceptance of Extraneous Untrusted Data With Trusted Data

Affects ISC BIND 9Source CVE Database V5

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Not known to be exploited · CVSS 5.8 Medium.

Data as of 31 Oct 2026, 20:20 UTC

CVSS 3.1 base score
5.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:N/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 16 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
ISCBIND 9Affected
  • >=9.11.0 <=9.18.50
  • >=9.20.0 <=9.20.27
  • >=9.21.0 <=9.21.25
  • >=9.11.3-S1 <=9.18.50-S1
  • >=9.20.9-S1 <=9.20.27-S1
Fixed in–
GitHubisc/bind9pkg:github/isc/bind9Other threatsAffected
  • >=9.11.0 <=9.18.50
  • >=9.20.0 <=9.20.27
  • >=9.21.0 <=9.21.25
  • >=9.11.3-S1 <=9.18.50-S1
  • >=9.20.9-S1 <=9.20.27-S1
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until an official fix is available, administrators should carefully review zone data for malformed NS or DNAME nodes above their origin and remove or correct such entries to prevent the issue. Monitoring and validation of zone files can help mitigate the risk.

Description

CVE-2026-78301 is a medium severity vulnerability in ISC BIND 9 affecting versions from 9.11.0 through 9.21.25 and related S1 versions. It involves the handling of malformed DNS zones containing NS or DNAME nodes above their origin, which are incorrectly treated as zone cuts. This causes queries within the configured zone to lose authoritative status and return delegations outside the zone. On recursive servers, this can lead to caching of attacker-supplied data affecting names outside the configured zone. The issue persists as long as the malformed zone remains in the zone database.

References

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