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VulnerabilityPublished Updated

CVE-2026-3104: ISC BIND 9 · Missing Release of Resource after Effective Lifetime

Affects ISC BIND 9Source CVE Database V5

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Not known to be exploited · CVSS 7.5 High · fixed in 9.21.20 : patch ISC BIND 9 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.7% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 9.21.20, 9.21.0, 9.20.21 +1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Mar 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 30 Oct 2026.

What to do

Upgrade isc/bind9 to 9.21.20, 9.21.0, 9.20.21 or 9.20.0.

Affected software

ProductAffectedFixed in
ISCBIND 9Affected
  • >=9.20.0 <=9.20.20
  • >=9.21.0 <=9.21.19
  • >=9.20.9-S1 <=9.20.20-S1
Fixed in–
GitHubisc/bind9pkg:github/isc/bind9Other threatsAffected
  • <9.20.0
  • >=9.20.0 <9.20.21
  • <9.21.0
  • >=9.21.0 <9.21.20
Fixed in
  • 9.20.0
  • 9.20.21
  • 9.21.0
  • 9.21.20

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

AI-suggested

The Red Hat advisories reference this CVE but do not explicitly confirm a fix or update addressing it. If you cannot patch yet, consider limiting exposure of vulnerable BIND resolvers to untrusted networks to reduce risk.

Description

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.

References

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