CVE-2026-58218Network attack vector

TSIG denial of service via TKEY cache exhaustion

Published Jul 30, 2026 · Updated Jul 30, 2026

Resource exhaustion in Samba allows remote attackers to block TSIG-signed DNS queries via unauthenticated TKEY registration requests. The internal DNS server inserts arbitrary TKEY names into its rejection-filter cache before rejecting requests that lack authentication. Repeated requests evict legitimate entries, so network access to the internal DNS service is sufficient to interrupt TSIG authentication; BIND9 DLZ is not affected.

CVSS severity5.3
Medium
EPSS probability0.62%
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 Samba allows remote attackers to block TSIG-signed DNS queries via unauthenticated TKEY registration requests. The internal DNS server inserts arbitrary TKEY names into its rejection-filter cache before rejecting requests that lack authentication. Repeated requests evict legitimate entries, so network access to the internal DNS service is sufficient to interrupt TSIG authentication; BIND9 DLZ is not affected.

The record

CVE
CVE-2026-58218
Published
Jul 30, 2026
Updated
Jul 30, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-410, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 30, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 30, 2026Record 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

5.3Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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-410Insufficient Resource Pool
T1499.003Application 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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