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BindApplication · Isc

CVE-2022-3924

HIGH · 7.5 CVSS v3.1 Published 2023-01-26
Fix available
A fix is available. Upgrade to 9.16.37 / 9.18.11 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
This issue can affect BIND 9 resolvers with `stale-answer-enable yes;` that also make use of the option `stale-answer-client-timeout`, configured with a value greater than zero. If the resolver receives many queries that require recursion, there will be a corresponding increase in the number of clients that are waiting for recursion to complete. If there are sufficient clients already waiting when a new client query is received so that it is necessary to SERVFAIL the longest waiting client (see BIND 9 ARM `recursive-clients` limit and soft quota), then it is possible for a race to occur between providing a stale answer to this older client and sending an early timeout SERVFAIL, which may cause an assertion failure. This issue affects BIND 9 versions 9.16.12 through 9.16.36, 9.18.0 through 9.18.10, 9.19.0 through 9.19.8, and 9.16.12-S1 through 9.16.36-S1.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A race condition in BIND 9 resolvers with `stale-answer-enable yes` and `stale-answer-client-timeout` greater than zero can cause an assertion failure when a SERVFAIL is sent to the longest-waiting client while simultaneously providing a stale answer, leading to denial of service.

MitigationUpgrade BIND 9 to version 9.16.37, 9.18.11, or 9.19.9 or later, or disable the `stale-answer-client-timeout` option by setting it to 0.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
BindApplication
Affected:>= 9.16.12, < 9.16.37>= 9.18.0, < 9.18.11>= 9.19.0, < 9.19.9= 9.16.12= 9.16.13= 9.16.14= 9.16.21= 9.16.32= 9.16.36

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed BIND version
    Run `named -v` or `named -V` to see the BIND version number
    Affected if The version falls within the affected ranges: 9.16.12 to 9.16.36, 9.18.0 to 9.18.10, or 9.19.0 to 9.19.8
  2. Verify stale-answer-enable configuration
    Inspect the named.conf file (commonly /etc/named.conf or /etc/bind/named.conf) and search for `stale-answer-enable`
    Affected if The option is set to `yes` or `true`
  3. Verify stale-answer-client-timeout setting
    In the same named.conf file, search for `stale-answer-client-timeout` and note its numeric value
    Affected if The value is set to a number greater than 0 (zero)

The environment is affected only if running a vulnerable BIND 9 version AND both stale-answer-enable is enabled AND stale-answer-client-timeout is set to a value greater than zero.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 9.16.37 / 9.18.11 / 9.19.9 or later
Fixed in 9.16.379.18.119.19.9
Interim mitigation

Upgrade BIND 9 to version 9.16.37, 9.18.11, or 9.19.9 or later, or disable the `stale-answer-client-timeout` option by setting it to 0.

Recommended fix High confidence

Upgrade to BIND 9.16.37+, 9.18.11+, or 9.19.9+ depending on your release branch

  1. 1. Identify the current BIND 9 version by running `named -v` or `bind -v`
  2. 2. Determine which release series you are running (9.16.x, 9.18.x, or 9.19.x)
  3. 3. For BIND 9.16.x: Upgrade to version 9.16.37 or later
  4. 4. For BIND 9.18.x: Upgrade to version 9.18.11 or later
  5. 5. For BIND 9.19.x: Upgrade to version 9.19.9 or later
  6. 6. After upgrade, verify the fix by checking `named -v` shows the patched version
  7. 7. Test DNS resolution functionality to confirm the resolver operates correctly
  8. 8. If immediate upgrade is not possible, mitigate by setting `stale-answer-client-timeout 0;` in the options block of named.conf (this disables the vulnerable code path)
Caveat Upgrading BIND may introduce changes to behavior or configuration requirements; review the release notes for your target version for any breaking changes

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Bind Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2022-3924 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data