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Reachable AssertionWeakness · CWE-617

CVE-2025-13878

HIGH · 7.5 CVSS v3.1 Published 2026-01-21
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
Malformed BRID/HHIT records can cause `named` to terminate unexpectedly. This issue affects BIND 9 versions 9.18.40 through 9.18.43, 9.20.13 through 9.20.17, 9.21.12 through 9.21.16, 9.18.40-S1 through 9.18.43-S1, and 9.20.13-S1 through 9.20.17-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 denial of service vulnerability in BIND 9 where malformed BRID (Border Router ID) or HHIT (Home Agent ID) DNS records cause the named DNS server to crash and terminate unexpectedly. The vulnerability is triggered by processing specially crafted DNS records.

MitigationUpdate BIND 9 to a patched version (9.18.44+, 9.20.18+, 9.21.17+, or corresponding -S1 releases) or implement DNS traffic filtering at network perimeter to block malformed records.

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

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. Determine installed BIND 9 version
    Run 'named -v' or 'named -V' to obtain the exact version number of the BIND 9 server software
    Affected if The version is earlier than 9.18.44, 9.20.18, or 9.21.17 (specifically any 9.18.x before 9.18.44, any 9.20.x before 9.20.18, or any 9.21.x before 9.21.17)
  2. Verify BIND 9 is running and accepting DNS queries
    Check if the named process is active and listening on port 53 using commands such as 'ps aux | grep named' and 'netstat -ulnp | grep :53' or 'ss -ulnp | grep :53'
    Affected if The server is running and processing DNS queries; this is required for the malformed BRID/HHIT records to reach the server
  3. Confirm whether recursion or forwarding is enabled
    Inspect the named.conf configuration file for 'recursion yes;' or 'allow-recursion' and 'forwarders' statements, which indicate the server processes recursive DNS queries from clients
    Affected if Recursion or forwarding is enabled, as this allows the server to process external DNS responses containing the malformed records
  4. Review logs for unexpected terminations
    Examine system logs (such as /var/log/messages, /var/log/syslog, or BIND query logs) for messages indicating named crashes, assertion failures, or unexpected process termination occurring after receiving DNS responses
    Affected if The server has terminated unexpectedly with no clear cause, particularly after processing potentially malicious DNS responses

You are affected if you are running an unpatched BIND 9 version (below 9.18.44, 9.20.18, or 9.21.17) and your server is operational and processing DNS queries, as malformed BRID/HHIT records in malicious DNS responses can trigger the denial of service.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update BIND 9 to a patched version (9.18.44+, 9.20.18+, 9.21.17+, or corresponding -S1 releases) or implement DNS traffic filtering at network perimeter to block malformed records.

Recommended fix High confidence

BIND 9.18.44+, 9.20.18+, or 9.21.17+ (depending on your current branch)

  1. 1. Identify the currently installed BIND 9 version by running `named -v` or `rpm -q bind`
  2. 2. Determine which release branch you are running (9.18.x, 9.20.x, or 9.21.x, or their -S1 variants)
  3. 3. For BIND 9.18.x (including 9.18.40-9.18.43 and 9.18.40-S1 to 9.18.43-S1): upgrade to BIND 9.18.44 or later
  4. 4. For BIND 9.20.x (including 9.20.13-9.20.17 and 9.20.13-S1 to 9.20.17-S1): upgrade to BIND 9.20.18 or later
  5. 5. For BIND 9.21.x (including 9.21.12-9.21.16): upgrade to BIND 9.21.17 or later
  6. 6. Obtain the appropriate patched version from downloads.isc.org or your Linux distribution's package repository
  7. 7. Install the new package using your system's package manager (e.g., `apt-get install bind9` or `yum update bind`)
  8. 8. Restart the named service using `systemctl restart named` or the appropriate command for your system

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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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-2025-13878 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
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