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Fencer Vulns
high 7.5

CVE-2026-69184 json

c-ares: CPU-exhaustion denial of service via unbounded DNS name compression pointer chains

published 2026-09-18 51 d ago modified 2026-09-24 45 d ago also EUVD-2026-83213

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_name_parse() enforces backward DNS compression pointers but does not bound the total pointer hops or assembled name length. A malicious DNS server can send a response containing a long descending pointer chain and many resource records whose NAME or RDATA fields refer to the chain, causing repeated decompression work that grows quadratically with message size. A single crafted response can stall the single-threaded c-ares event loop and deny DNS resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7.

Patch / fix

  • c-ares_project c-ares 1.34.7
  • c-ares c-ares 1.34.7
  • c-ares Debian 14 1.34.7-1

debian advisories DEBIAN-CVE-2026-69184

  • c-ares Ubuntu 22.04 LTS 1.18.1-1ubuntu0.22.04.4
  • c-ares Ubuntu 24.04 LTS 1.27.0-1.0ubuntu1.1
  • c-ares Ubuntu 26.04 LTS 1.34.6-1ubuntu0.2
  • c-ares Ubuntu Pro 16.04 LTS 1.10.0-3ubuntu0.2+esm4
  • c-ares Ubuntu Pro 18.04 LTS 1.14.0-1ubuntu0.2+esm3
  • c-ares Ubuntu Pro 20.04 LTS 1.15.0-1ubuntu0.5+esm1

ubuntu advisories UBUNTU-CVE-2026-69184

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • c-ares hummingbird 1 1.34.8-2.hum1

red hat advisories RHSA-2026:40574

  • c-ares SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 1.34.8-150000.3.29.1
  • c-ares SLES for SAP applications 16.0, SLES 16.0 1.34.8-160000.1.1
  • c-ares Linux Micro 6.1 1.34.8-slfo.1.1_1.1
  • c-ares Linux Micro 6.0 1.34.8-1.1
  • libcares2 SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 1.9.1-9.24.1

suse advisories SUSE-SU-2026:4021-1SUSE-SU-2026:23597-1SUSE-SU-2026:23414-1SUSE-SU-2026:3872-1SUSE-SU-2026:23364-1

  • c-ares openSUSE Leap 16.0 1.34.8-160000.1.1
  • c-ares openSUSE Tumbleweed 1.34.8-1.1

opensuse advisories openSUSE-SU-2026:21721-1openSUSE-SU-2026:11593-1

  • c-ares Azure Linux 3.0 1.34.8-1

azure linux advisories AZL-103307

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-69184 updated cvss 7.5

c-ares: c-ares: CPU exhaustion denial of service via unbounded DNS name compression pointer chains

  • Red Hat Enterprise Linux 10 c-ares Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available
  • Red Hat OpenShift Service Mesh 3 istio-proxy, istio-proxy-selinux
    under investigation
  • Red Hat Hardened Images c-ares 1.34.8-2.hum1
    fixed: vendor fix RHSA-2026:40574
  • Red Hat Enterprise Linux 6 c-ares Red Hat Enterprise Linux 7 c-ares Red Hat Enterprise Linux 8 npm, c-ares, nodejs, nodejs-libs, nodejs-nodemon, nodejs-full-i18n, +2 more Red Hat Enterprise Linux 9 npm, c-ares, nodejs, nodejs-libs, nodejs-full-i18n Red Hat Enterprise Linux 10 nodejs22
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
51 d ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • c-ares c-ares

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.