UBUNTU-CVE-2025-31498 (CVE-2025-31498)

Vulnerability from osv_ubuntu – Published: 2025-04-08 14:15 – Updated: 2025-09-08 17:08 – Source website
Withdrawn 2026-01-20 VLAI
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"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.