Use After Free Affecting libcares2 package, versions <1.34.8-150000.3.29.1


Severity

Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.59% (47th percentile)

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  • Snyk IDSNYK-SLES156-LIBCARES2-19779810
  • published14 Sept 2026
  • disclosed7 Sept 2026

Introduced: 7 Sep 2026

CVE-2025-31498  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade SLES:15.6 libcares2 to version 1.34.8-150000.3.29.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libcares2 package and not the libcares2 package as distributed by SLES. See How to fix? for SLES:15.6 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1