{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-89550",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-09-11T19:38:34.723Z",
        "datePublished": "2026-09-11T19:44:24.572Z",
        "dateUpdated": "2026-10-19T08:48:43.080Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-10-19T08:48:43.080Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: svcauth_gss: enforce krb5 token minimum length\n\nsvcauth_gss_unwrap_priv() validates only an upper bound on the\nwire-supplied opaque length before handing the buffer to\ngss_unwrap():\n\n    if (len > xdr_stream_remaining(xdr))\n            goto unwrap_failed;\n    offset = xdr_stream_pos(xdr);\n    ...\n    maj_stat = gss_unwrap(ctx, offset, offset + len, buf);\n\nThe wire value `len` flows unchanged as the upper bound into the\nkrb5 unwrap path, so a len in [0, 16] passes this check and is\nhanded to gss_unwrap(). For a krb5 v2 context that lands in\ngss_krb5_unwrap_v2(), which reads the 16-byte RFC 4121 token\nheader fields at ptr+4 and ptr+6 and then calls rotate_left()\nbefore any integrity check. With a sub-header length the header\nreads run past the token, and _rotate_left()'s `shift %= buf->len`\npath can divide by zero when buf->len has been driven to zero by\nthe truncated token. A header-only token (len == 16) is equally\ninvalid: with a non-zero RRC field and the opaque blob ending at\nthe XDR buffer boundary, rotate_left() builds a zero-length\nsubbuffer, reaching the same division.\n\nReject the token at the server entry point before it reaches the\nkrb5 unwrap core. A valid sealed RFC 4121 token must contain\nthe 16-byte header plus at least some encrypted payload.\n\nFix by adding a minimum-length check immediately after the\nexisting upper-bound check:\n\n    if (len <= GSS_KRB5_TOK_HDR_LEN)\n            goto unwrap_failed;"
                }
            ],
            "metrics": [
                {
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                        "baseScore": 9.8,
                        "baseSeverity": "CRITICAL"
                    },
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "AV:N - svcauth_gss_unwrap_priv() is reached from in-kernel nfsd over TCP/2049 (svc_authenticate → svcauth_gss_accept) and from the NFSv4.0 RPC_AUTH_GSS callback service, so a remote RPCSEC_GSS peer delivers the short krb5 wrap token over the network.\nAC:L - A single RPCSEC_GSS DATA Call with gc_svc=PRIVACY and opaque length in [0, 16] plus a non-zero RRC in the cleartext RFC 4121 header deterministically hits gss_krb5_unwrap_v2() rotate_left() u32 wrap and shift%=0; no race or attacker-uncontrollable layout is required.\nPR:N - A malicious NFS server that already shares a krb5p GSS context can send a crafted NFSv4.0 GSS callback into the client's svcauth_gss_unwrap_priv() with no account or capability on the victim. That peer path is the highest-severity reachability.\nUI:N - nfsd unwraps the Call in the service thread with no local user action. On the client, the NFSv4.0 GSS callback path runs from the callback service thread once an NFS/RPCSEC_GSS mount exists; no additional mount, click, or open is required at attack time.\nS:U - The out-of-bounds accesses, divide-by-zero, and underflowed memmove corrupt host kernel SUNRPC/GSS state on the machine processing the RPC. This is ordinary same-host kernel impact, not a VM escape, IOMMU bypass, or other changed-scope boundary.\nC:H - Short tokens make gss_krb5_unwrap_v2() read EC/RRC past the token, and the dead BUG_ON lets unsigned movelen underflow into a ~UINT_MAX-byte memmove that copies kernel memory beyond the receive head; that unbounded read is C:H per kernel CNA memory-corruption guidance.\nI:H - The same underflowed memmove() writes near 4GiB through the RPC receive head, an out-of-bounds write exploitable for control-flow hijack. rotate_left() also ignores xdr_buf_subsegment() failure after u32 wrap and then writes through a subbuf whose length has wrapped.\nA:H - _rotate_left() does shift %= buf->len on a zero-length subbuffer (header-only token at the XDR boundary), a divide-by-zero oops/panic; the UINT_MAX memmove and wrapped-length rotate loop hang or oops nfsd/callback threads, and the attacker can repeat the RPC to deny service."
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/sunrpc/auth_gss/svcauth_gss.c"
                    ],
                    "versions": [
                        {
                            "version": "7c9fdcfb1b64c47ed618c103b617af3f86e1239c",
                            "lessThan": "0ea5b0c7f212c2772d32c2b88287b89a9cdf6edd",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "7c9fdcfb1b64c47ed618c103b617af3f86e1239c",
                            "lessThan": "dd6afc6cab8c5d387d1ed2f069562ef7bdadd651",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "7c9fdcfb1b64c47ed618c103b617af3f86e1239c",
                            "lessThan": "de942dd8c2c8358bcad04ce44271954c48924423",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "7c9fdcfb1b64c47ed618c103b617af3f86e1239c",
                            "lessThan": "2eed1e6a976a44015c3ee78841fe336796e2b21c",
                            "status": "affected",
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                            "lessThan": "a919c5c88769cf8fb3ec071e6078d830bf512489",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/sunrpc/auth_gss/svcauth_gss.c"
                    ],
                    "versions": [
                        {
                            "version": "2.6.18",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "2.6.18",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.157",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.109",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.50",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.4",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "2.6.18",
                                    "versionEndExcluding": "6.6.157"
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                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "2.6.18",
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                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "2.6.18",
                                    "versionEndExcluding": "6.18.50"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/0ea5b0c7f212c2772d32c2b88287b89a9cdf6edd"
                },
                {
                    "url": "https://git.kernel.org/stable/c/dd6afc6cab8c5d387d1ed2f069562ef7bdadd651"
                },
                {
                    "url": "https://git.kernel.org/stable/c/de942dd8c2c8358bcad04ce44271954c48924423"
                },
                {
                    "url": "https://git.kernel.org/stable/c/2eed1e6a976a44015c3ee78841fe336796e2b21c"
                },
                {
                    "url": "https://git.kernel.org/stable/c/a919c5c88769cf8fb3ec071e6078d830bf512489"
                }
            ],
            "title": "SUNRPC: svcauth_gss: enforce krb5 token minimum length",
            "x_generator": {
                "engine": "bippy-1.2.0"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "id": "CVE-2026-89550",
                                "role": "CISA Coordinator",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "yes"
                                    },
                                    {
                                        "Technical Impact": "total"
                                    }
                                ],
                                "version": "2.0.3",
                                "timestamp": "2026-10-16T19:23:48.643149Z"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-10-16T19:26:43.119Z"
                }
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    }
}