CVE-2026-69186VulnerabilityPublished 18 Sep 2026Updated 21 Oct 2026

C ares: Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before

Affects c-aresSource GCVE Database

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Not known to be exploited · CVSS 5.3 Medium · fixed in 1.27.0-1.0ubuntu1.1 : update c-ares when convenient.

Data as of 7 Nov 2026, 23:24 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.27.0-1.0ubuntu1.1, 1.34.6-1ubuntu0.2

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 8 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade the Ubuntu c-ares to 1.27.0-1.0ubuntu1.1 (package) or 1.34.6-1ubuntu0.2 (package).

Affected software

Product	Affected	Fixed in
Ubuntu 26.04 LTSc-ares`pkg:deb/ubuntu/c-ares?arch=source&distro=resolute`Other threats	Affected <1.34.6-1ubuntu0.2	Fixed in 1.34.6-1ubuntu0.2
Ubuntu 24.04 LTSc-ares`pkg:deb/ubuntu/c-ares?arch=source&distro=noble`Other threats	Affected <1.27.0-1.0ubuntu1.1	Fixed in 1.27.0-1.0ubuntu1.1
Ubuntu 22.04 LTSc-ares`pkg:deb/ubuntu/c-ares?arch=source&distro=jammy`Other threats	Affected 1.17.1-1ubuntu1 – 1.18.1-1ubuntu0.22.04.3 6 affected builds	Fixed in–
Ubuntu 20.04 LTSc-ares`pkg:deb/ubuntu/c-ares?arch=source&distro=focal`Other threats	Affected 1.15.0-1build1 – 1.15.0-1ubuntu0.5 6 affected builds	Fixed in–
Ubuntu Pro 18.04 LTSc-ares`pkg:deb/ubuntu/c-ares?arch=source&distro=esm-infra/bionic`Other threats	Affected 1.13.0-2 – 1.14.0-1ubuntu0.2+esm2 7 affected builds	Fixed in–
Ubuntu Pro 16.04 LTSc-ares`pkg:deb/ubuntu/c-ares?arch=source&distro=esm-infra/xenial`Other threats	Affected 1.10.0-2 – 1.10.0-3ubuntu0.2+esm3 7 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade to c-ares version 1.34.7 or later, where this issue is fixed. No other mitigation is indicated by the vendor advisory.

Description

c-ares versions prior to 1.34.7 contain a vulnerability in the ares_dns_parse() function where attacker-controlled DNS response fields (ANCOUNT, NSCOUNT, ARCOUNT) are trusted before verifying the response length. This can lead to excessive heap memory allocation for small messages, causing resource exhaustion and potential denial of service in name resolution. The issue does not cause memory corruption or information disclosure and is fixed in version 1.34.7.

Impact

An attacker can send malicious DNS responses that cause the vulnerable c-ares library to allocate excessive heap memory repeatedly, leading to degraded performance or denial of service of name resolution. There is no memory corruption or information disclosure associated with this vulnerability.

Summary

The asynchronous resolver library c-ares has a vulnerability in versions before 1.34.7 where the ares_dns_parse() function trusts the ANCOUNT, NSCOUNT, and ARCOUNT fields in DNS responses without confirming the response contains enough bytes for the claimed records. Because process_answer() parses the response before validating the transaction ID and question, a malicious DNS response can cause disproportionate heap memory allocation via ares_dns_record_rr_prealloc() and ares_array_set_size(). Repeated exploitation can degrade or deny DNS resolution service. This vulnerability is addressed in c-ares version 1.34.7.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Sep 2026, 06:46 UTC

Technical details

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