CVE-2026-89543 affecting package kernel 6.6.157.1-1

{
  "id": "910895c0f4995260cf2e1a2475b676646cb354d5b6cd138551986eef0b821de7",
  "url": "https://osv.dev/vulnerability/AZL-100283",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2026-89543 affecting package kernel 6.6.157.1-1",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: sunrpc: fix use-after-free in __rpc_clnt_handle_event and __rpc_clnt_remove_pipedir Normal client creation goes through rpc_setup_pipedir(), which records clnt->pipefs_sb, but the mount-event path in __rpc_clnt_handle_event() calls rpc_setup_pipedir_sb() directly and never refreshes that field. The umount path also removes the directory without clearing clnt->pipefs_sb. After a late pipefs mount or any remount, rpc_clnt_remove_pipedir() compares the current superblock against a stale pipefs_sb pointer and skips cleanup, leaving pipefs dentries whose inode private data still points at a freed rpc_clnt, leading to a potential use-after-free during subsequent rpc_info_open() or rpc_show_info() calls. Fix this by properly updating clnt->pipefs_sb upon mount events and clearing it during unmount or failure paths.",
    "evidence": "osv:AZL-100283",
    "products": [
      {
        "name": {
          "value": "kernel",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "AZL-100283",
      "aliases": [
        "AZL-100283"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "6.6.157.1-1"
                }
              ]
            }
          ],
          "package": {
            "name": "kernel",
            "purl": "pkg:rpm/azure-linux/kernel",
            "ecosystem": "Azure Linux:3"
          },
          "database_specific": {
            "source": "https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-100283.json"
          }
        }
      ],
      "modified": "2026-10-22T05:35:55Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-89543"
      ],
      "references": [
        "https://nvd.nist.gov/vuln/detail/CVE-2026-89543"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-89543",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 404396,
  "published_at": "2026-09-11T20:19:37+00:00"
}