{
  "cveId": "CVE-2026-89537",
  "url": "https://patchblox.com/security/cve/CVE-2026-89537",
  "summary": "CVE-2026-89537 is fixed in 11 products on 1 platform, first by DEBIAN-CVE-2026-89537, released September 23, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  SUNRPC: Reject short RFC 4121 MIC tokens in gss_krb5_verify_mic_v2  gss_krb5_verify_mic_v2() reads the token ID at ptr[0..1], the flags byte at ptr[2], and padding at ptr[3..7], then passes ptr \u002B GSS_KRB5_TOK_HDR_LEN and cksum_len to gss_krb5_mic_build_sg(). None of these accesses check read_token-\u003Elen first.  The minimum safe token size is GSS_KRB5_TOK_HDR_LEN (16) plus ctx-\u003Ekrb5e-\u003Ecksum_len (12-24, depending on the enctype).  All callers accept shorter tokens from the wire:   - gss_unwrap_resp_integ() enforces only an upper bound    (offset \u002B len \u003C= rcv_buf-\u003Elen) before allocating    mic.data = kmalloc(len) and passing it to gss_verify_mic().    A malicious NFS server can therefore supply a short checksum    opaque, producing a small slab allocation that the Kerberos MIC    verifier reads past.   - gss_validate() enforces only len \u003C= RPC_MAX_AUTH_SIZE (400)    before passing the wire-supplied length to    gss_validate_seqno_mic(), which constructs a mic xdr_netobj    and calls gss_verify_mic().   - svcauth_gss_verify_header() enforces only    checksum.len \u003E= XDR_UNIT (4 bytes) before dispatching to    gss_verify_mic().   - svcauth_gss_unwrap_integ() checks only that the checksum fits    in gsd-\u003Egsd_scratch.  Add a length guard at the top of gss_krb5_verify_mic_v2(), before any ptr[] access or scatterlist construction.  Well-formed MIC tokens from gss_krb5_get_mic_v2() already have exactly GSS_KRB5_TOK_HDR_LEN \u002B cksum_len bytes, so valid traffic is unaffected.",
  "published": "2026-09-11T20:19:36Z",
  "severity": "Moderate",
  "cvss": 9.1,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
  "epss": 0.0073,
  "epssPercentile": 0.54527,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-89537",
  "fixes": [
    {
      "platform": "linux",
      "product": "kernel-64kb",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.90.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-azure",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.90.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-default",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.90.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-default-base",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.90.1.150700.17.51.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-docs",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.90.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-livepatch-SLE15-SP7_Update_24",
      "release": "sles 15.7",
      "fixedVersion": "1-150700.15.3.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-obs-build",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.90.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-source",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.90.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-syms",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.90.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-zfcpdump",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.90.1",
      "fix": "SUSE-SU-2026:5091-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-5091-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.115-2",
      "fix": "DEBIAN-CVE-2026-89537",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-89537",
      "released": "2026-09-23T19:19:02Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.6-1",
      "fix": "DEBIAN-CVE-2026-89537",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-89537",
      "released": "2026-09-23T19:19:02Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T01:18:40Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}