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FedoraOperating system · Fedoraproject

CVE-2020-8623

HIGH · 7.5 CVSS v3.1 Published 2020-08-21
Fix available
A fix is available. Upgrade to 2.2.2-5027 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
In BIND 9.10.0 -> 9.11.21, 9.12.0 -> 9.16.5, 9.17.0 -> 9.17.3, also affects 9.10.5-S1 -> 9.11.21-S1 of the BIND 9 Supported Preview Edition, An attacker that can reach a vulnerable system with a specially crafted query packet can trigger a crash. To be vulnerable, the system must: * be running BIND that was built with "--enable-native-pkcs11" * be signing one or more zones with an RSA key * be able to receive queries from a possible attacker

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 allows remote attackers to crash the DNS server by sending a specially crafted query packet. The server is only vulnerable if it was compiled with PKCS#11 support (--enable-native-pkcs11) and is signing one or more zones using RSA keys.

MitigationUpgrade BIND to a patched version (9.11.22, 9.16.6, 9.17.4 or later). If upgrading is not immediately possible, verify whether the server meets the vulnerable conditions (PKCS11 build flag and RSA-signed zones) and consider restricting query access as a temporary measure.

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
FedoraOperating system
Affected:= 31= 32
Debian LinuxOperating system
Affected:= 9.0= 10.0
Ubuntu LinuxOperating system
Affected:= 16.04= 18.04= 20.04
BindApplication
Affected:>= 9.10.0, <= 9.11.21>= 9.12.1, <= 9.16.5>= 9.17.0, <= 9.17.3= 9.10.5= 9.11.21
LeapOperating system
Affected:= 15.1= 15.2
Dns ServerApplication
Affected:< 2.2.2-5027
Steelstore Cloud Integrated StorageApplication
Affected:all versions

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. Identify BIND version
    Run 'named -v' or 'named -V' to retrieve the installed BIND version, or check the package manager for the bind package version
    Affected if The version falls within any of these ranges: 9.10.0-9.11.21, 9.12.1-9.16.5, 9.17.0-9.17.3, or equals 9.10.5 or 9.11.21
  2. Check for PKCS#11 support in build
    Examine the output of 'named -V' for '--enable-native-pkcs11' or review the build configuration used when compiling BIND
    Affected if The build includes PKCS#11 support (--enable-native-pkcs11 flag was used)
  3. Identify active signing keys
    Review the zone configuration files (typically in /etc/bind/zones/ or /etc/named.d/) and inspect the keys in use via 'named-checkconf -z' or by examining the key files in the keys directory
    Affected if Any zone is configured to sign with an RSA-based algorithm (RSASHA1, RSASHA256, RSASHA512, or similar RSA variants)
  4. Verify DNS server is internet-facing
    Review network configuration to confirm the DNS server accepts queries from external or untrusted networks
    Affected if The server is accessible from networks where untrusted users can send DNS queries

If BIND version is in the affected range, was compiled with PKCS#11 support, and is actively signing zones with RSA keys, the server is vulnerable to remote crash via crafted queries.

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.

From vendor data
Upgrade available Upgrade to 2.2.2-5027 or later
Fixed in 2.2.2-5027
Interim mitigation

Upgrade BIND to a patched version (9.11.22, 9.16.6, 9.17.4 or later). If upgrading is not immediately possible, verify whether the server meets the vulnerable conditions (PKCS11 build flag and RSA-signed zones) and consider restricting query access as a temporary measure.

Fix this in Fedora Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2020-8623 in production — separate from our analysis above.

No notes yet

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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