Description
c-ares is an asynchronous resolver library. From 1.32.3 through 1.34.4, there is a use-after-free in read_answers() when process_answer() may re-enqueue a query either due to a DNS Cookie Failure or when the upstream server does not properly support EDNS, or possibly on TCP queries if the remote closed the connection immediately after a response. If there was an issue trying to put that new transaction on the wire, it would close the connection handle, but read_answers() was still expecting the connection handle to be available to possibly dequeue other responses. In theory a remote attacker might be able to trigger this by flooding the target with ICMP UNREACHABLE packets if they also control the upstream nameserver and can return a result with one of those conditions, this has been untested. Otherwise only a local attacker might be able to change system behavior to make send()/write() return a failure condition. This vulnerability is fixed in 1.34.5.
Published: 2025-04-08
Score: 8.3 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
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Remediation

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Tracking

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Advisories
Source ID Title
EUVD EUVD EUVD-2025-10377 c-ares is an asynchronous resolver library. From 1.32.3 through 1.34.4, there is a use-after-free in read_answers() when process_answer() may re-enqueue a query either due to a DNS Cookie Failure or when the upstream server does not properly support EDNS, or possibly on TCP queries if the remote closed the connection immediately after a response. If there was an issue trying to put that new transaction on the wire, it would close the connection handle, but read_answers() was still expecting the connection handle to be available to possibly dequeue other responses. In theory a remote attacker might be able to trigger this by flooding the target with ICMP UNREACHABLE packets if they also control the upstream nameserver and can return a result with one of those conditions, this has been untested. Otherwise only a local attacker might be able to change system behavior to make send()/write() return a failure condition. This vulnerability is fixed in 1.34.5.
Ubuntu USN Ubuntu USN USN-7477-1 c-ares vulnerability
History

Wed, 14 May 2025 15:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_eus:9.4
Vendors & Products Redhat rhel Eus

Wed, 14 May 2025 03:00:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:enterprise_linux:10.0

Mon, 05 May 2025 15:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat
Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:8
Vendors & Products Redhat
Redhat enterprise Linux

Thu, 17 Apr 2025 05:15:00 +0000

Type Values Removed Values Added
Metrics threat_severity

Important

threat_severity

Moderate


Wed, 09 Apr 2025 15:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H'}

threat_severity

Important


Tue, 08 Apr 2025 19:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 08 Apr 2025 15:45:00 +0000

Type Values Removed Values Added
References

Tue, 08 Apr 2025 14:00:00 +0000

Type Values Removed Values Added
Description c-ares is an asynchronous resolver library. From 1.32.3 through 1.34.4, there is a use-after-free in read_answers() when process_answer() may re-enqueue a query either due to a DNS Cookie Failure or when the upstream server does not properly support EDNS, or possibly on TCP queries if the remote closed the connection immediately after a response. If there was an issue trying to put that new transaction on the wire, it would close the connection handle, but read_answers() was still expecting the connection handle to be available to possibly dequeue other responses. In theory a remote attacker might be able to trigger this by flooding the target with ICMP UNREACHABLE packets if they also control the upstream nameserver and can return a result with one of those conditions, this has been untested. Otherwise only a local attacker might be able to change system behavior to make send()/write() return a failure condition. This vulnerability is fixed in 1.34.5.
Title c-ares has a use-after-free in read_answers()
Weaknesses CWE-416
References
Metrics cvssV4_0

{'score': 8.3, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N'}


Subscriptions

Redhat Enterprise Linux Rhel Eus
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-04-08T18:40:36.081Z

Reserved: 2025-03-28T13:36:51.300Z

Link: CVE-2025-31498

cve-icon Vulnrichment

Updated: 2025-04-08T15:03:00.750Z

cve-icon NVD

Status : Deferred

Published: 2025-04-08T14:15:35.293

Modified: 2026-04-15T00:35:42.020

Link: CVE-2025-31498

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-04-08T13:53:11Z

Links: CVE-2025-31498 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses