CVE-2023-50868Network attack vector

DNS service interruption via NSEC3 hash exhaustion

Published Feb 14, 2024 · Updated Nov 4, 2025

Resource exhaustion in BIND 9 allows remote attackers to interrupt DNS resolution via crafted NSEC3 responses on validating resolvers. Closest-encloser proof processing repeatedly computes SHA-1 hashes for attacker-controlled NSEC3 iterations instead of bounding exceptionally complex DNSSEC validation. An unauthenticated remote attacker must flood a DNSSEC-validating resolver with random-subdomain queries, consuming CPU and denying legitimate clients resolution.

CVSS severity7.5
High
EPSS probability81.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in BIND 9 allows remote attackers to interrupt DNS resolution via crafted NSEC3 responses on validating resolvers. Closest-encloser proof processing repeatedly computes SHA-1 hashes for attacker-controlled NSEC3 iterations instead of bounding exceptionally complex DNSSEC validation. An unauthenticated remote attacker must flood a DNSSEC-validating resolver with random-subdomain queries, consuming CPU and denying legitimate clients resolution.

The record

CVE
CVE-2023-50868
Published
Feb 14, 2024
Updated
Nov 4, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-400, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 14, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5Internet Systems ConsortiumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.002Service Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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