ubuntu-cve-2025-31498
Vulnerability from osv_ubuntu
Published
2025-04-08 14:15
Modified
2025-09-08 17:08
Summary
Details

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.

Severity
8.3 (High)
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
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libc-ares-dev",
            "binary_version": "1.34.4-2.1ubuntu0.1"
          },
          {
            "binary_name": "libc-ares2",
            "binary_version": "1.34.4-2.1ubuntu0.1"
          },
          {
            "binary_name": "libcares2",
            "binary_version": "1.34.4-2.1ubuntu0.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.04",
        "name": "c-ares",
        "purl": "pkg:deb/ubuntu/c-ares@1.34.4-2.1ubuntu0.1?arch=source\u0026distro=plucky"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.34.4-2.1ubuntu0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.33.0-1",
        "1.34.2-1",
        "1.34.3-1",
        "1.34.4-1",
        "1.34.4-2.1"
      ]
    }
  ],
  "aliases": [],
  "details": "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.",
  "id": "UBUNTU-CVE-2025-31498",
  "modified": "2025-09-08T17:08:14Z",
  "published": "2025-04-08T14:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-31498"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-31498"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/c-ares/c-ares/security/advisories/GHSA-6hxc-62jh-p29v"
    },
    {
      "type": "REPORT",
      "url": "http://www.openwall.com/lists/oss-security/2025/04/08/3"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/c-ares/c-ares/commit/29d38719112639d8c0ba910254a3dd4f482ea2d1"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/c-ares/c-ares/pull/821"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-7477-1"
    }
  ],
  "related": [
    "USN-7477-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2025-31498"
  ],
  "withdrawn": "2026-01-20T05:27:25Z"
}



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