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GHSA-J7J8-RMPG-46W5

Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-11 21:31
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

SUNRPC: reject duplicate CREDS_VALUE options

gssx_dec_option_array() walks the wire-supplied option array and, for every entry whose name matches CREDS_VALUE, calls gssx_dec_linux_creds() on the same struct svc_cred. That helper unconditionally installs a fresh groups_alloc() result into creds->cr_group_info without releasing whatever pointer was already there:

for (i = 0; i < count; i++) {
    ... decode name ...
    if (length == sizeof(CREDS_VALUE) &&
        memcmp(p, CREDS_VALUE, sizeof(CREDS_VALUE)) == 0) {
        err = gssx_dec_linux_creds(xdr, creds);
        ...
    }
}

A reply that carries two CREDS_VALUE entries therefore overwrites cr_group_info on the second iteration and orphans the group_info allocated by the first call. The earlier free_creds path only releases the last cr_group_info via free_svc_cred(), so the first allocation's refcount stays at one and its kvmalloc-backed storage is leaked. No in-tree caller of gssp_accept_sec_context_upcall() expects more than one CREDS_VALUE per reply.

Fix by tracking whether a CREDS_VALUE option has already been decoded and returning -EINVAL on any subsequent match, so the free_creds path releases the single group_info that was installed.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-89539"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-11T20:19:36Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: reject duplicate CREDS_VALUE options\n\ngssx_dec_option_array() walks the wire-supplied option array and, for\nevery entry whose name matches CREDS_VALUE, calls\ngssx_dec_linux_creds() on the same struct svc_cred. That helper\nunconditionally installs a fresh groups_alloc() result into\ncreds-\u003ecr_group_info without releasing whatever pointer was already\nthere:\n\n    for (i = 0; i \u003c count; i++) {\n        ... decode name ...\n        if (length == sizeof(CREDS_VALUE) \u0026\u0026\n            memcmp(p, CREDS_VALUE, sizeof(CREDS_VALUE)) == 0) {\n            err = gssx_dec_linux_creds(xdr, creds);\n            ...\n        }\n    }\n\nA reply that carries two CREDS_VALUE entries therefore overwrites\ncr_group_info on the second iteration and orphans the group_info\nallocated by the first call. The earlier free_creds path only\nreleases the last cr_group_info via free_svc_cred(), so the first\nallocation\u0027s refcount stays at one and its kvmalloc-backed storage\nis leaked. No in-tree caller of gssp_accept_sec_context_upcall()\nexpects more than one CREDS_VALUE per reply.\n\nFix by tracking whether a CREDS_VALUE option has already been\ndecoded and returning -EINVAL on any subsequent match, so the\nfree_creds path releases the single group_info that was installed.",
  "id": "GHSA-j7j8-rmpg-46w5",
  "modified": "2026-09-11T21:31:31Z",
  "published": "2026-09-11T21:31:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89539"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2e4ce62385c1b8a887c5370af058ac7b52a8eaf9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7a1d0501cbb962beba23377035d667bf3c1726ee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9d94f046b23de0f77849ea69133063c949297e30"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f615b884310bf82d0014e3b5a92eb9aa88146685"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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