{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2026-89551",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-89551",
    "idYear": 2026,
    "status": "PUBLISHED",
    "publishedAt": "2026-09-11T19:44:25.327Z",
    "updatedAt": "2026-10-19T08:48:44.059Z",
    "importedAt": "2026-10-24T01:58:35.090Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "SUNRPC: xdr_buf_trim: clamp buf->len to avoid underflow",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: xdr_buf_trim: clamp buf->len to avoid underflow\n\nxdr_buf_trim() trims `len` bytes from the tail of an xdr_buf by\nwalking the tail, pages, and head iovecs.  Each per-section step\nuses min_t() so it never removes more bytes than that section\nholds, but the final accounting at the fix_len label subtracts the\ntotal bytes actually consumed from buf->len without any clamp:\n\n    fix_len:\n            buf->len -= (len - trim);\n\nWhen the caller has set buf->len to a value smaller than the sum\nof the iov_lens, (len - trim) can exceed buf->len and the unsigned\nsubtraction wraps to near UINT_MAX.  gss_krb5_unwrap_v2() reaches\nxdr_buf_trim() in exactly that state:\n\n    buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;\n    buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip);\n    xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);\n\nbuf->len is a small wire-derived value while the iov_lens are at\npage scale, so the per-section loops legitimately consume far more\nbytes than buf->len records.  The wrapped buf->len then propagates\nas the authoritative stream bound into every downstream XDR\ndecoder.\n\nFix by clamping the decrement so buf->len bottoms out at zero:\n\n    buf->len -= min_t(unsigned int, buf->len, len - trim);\n\nOn the normal path where the iov_lens sum to buf->len, (len - trim)\nis always <= buf->len and the result is identical to before.  No\ncallers change behavior outside the underflow case.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "4c190e2f913f038c9c91ee63b59cd037260ba353",
              "status": "affected",
              "versionType": "git",
              "lessThan": "a3d77bcd974b8625d16bddf448cb3a1b5e37049c"
            },
            {
              "version": "4c190e2f913f038c9c91ee63b59cd037260ba353",
              "status": "affected",
              "versionType": "git",
              "lessThan": "fa16bbe987b47e771e52eeb1b4540f18d92496ac"
            },
            {
              "version": "4c190e2f913f038c9c91ee63b59cd037260ba353",
              "status": "affected",
              "versionType": "git",
              "lessThan": "a924ac4c78afab71bf82641afa3b62e0c4a8b55e"
            },
            {
              "version": "4c190e2f913f038c9c91ee63b59cd037260ba353",
              "status": "affected",
              "versionType": "git",
              "lessThan": "4bf59cb0ea5b0ddfbc46a1dc2fa78fc8b9986ce4"
            },
            {
              "version": "4c190e2f913f038c9c91ee63b59cd037260ba353",
              "status": "affected",
              "versionType": "git",
              "lessThan": "e6267cccd7b05cc514e57f2160aa8db85f5c2701"
            },
            {
              "version": "4c190e2f913f038c9c91ee63b59cd037260ba353",
              "status": "affected",
              "versionType": "git",
              "lessThan": "ad0cce80d4af2f74674e8b635d97aa3880e83da8"
            },
            {
              "version": "4c190e2f913f038c9c91ee63b59cd037260ba353",
              "status": "affected",
              "versionType": "git",
              "lessThan": "85e9602650e9df07190abe817cee3b4d9bc3df17"
            },
            {
              "version": "4c190e2f913f038c9c91ee63b59cd037260ba353",
              "status": "affected",
              "versionType": "git",
              "lessThan": "3f491306dcb673ff5e78e1044ba450c58978774e"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "3.9",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "3.9"
            },
            {
              "version": "5.10.270",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "version": "5.15.221",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "version": "6.1.188",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "version": "6.6.157",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "version": "6.12.109",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "version": "6.18.50",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "version": "7.2.4",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "version": "7.3",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}