CVE-2026-69186Network attack vector

Name-resolution denial of service via DNS count preallocation

Published Sep 18, 2026 · Updated Sep 18, 2026

Uncontrolled resource consumption in c-ares before 1.34.7 allows remote attackers to interrupt name resolution via malicious DNS responses. ares_dns_parse() trusts ANCOUNT, NSCOUNT, and ARCOUNT before checking message length, so a tiny packet makes record-array preallocation reserve about 15 MB. A malicious or on-path DNS server, or an off-path spoofer able to reach the query socket, must sustain responses to create repeated allocation and release cycles; the effect is service degradation or denial without memory corruption or disclosure.

CVSS severity5.3
Medium
EPSS probability0.52%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in c-ares before 1.34.7 allows remote attackers to interrupt name resolution via malicious DNS responses. ares_dns_parse() trusts ANCOUNT, NSCOUNT, and ARCOUNT before checking message length, so a tiny packet makes record-array preallocation reserve about 15 MB. A malicious or on-path DNS server, or an off-path spoofer able to reach the query socket, must sustain responses to create repeated allocation and release cycles; the effect is service degradation or denial without memory corruption or disclosure.

The record

CVE
CVE-2026-69186
Published
Sep 18, 2026
Updated
Sep 18, 2026
Vendor
c-ares Project
Product
c-ares
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.34.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

c-ares Project · c-aresversion=< 1.34.7

Published CVSS scores

5.3c-ares ProjectCVSS: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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 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
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

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Your stack

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