GHSA-HCPQ-G756-Q7PV
Vulnerability from github – Published: 2026-09-24 18:31 – Updated: 2026-09-25 06:30In the Linux kernel, the following vulnerability has been resolved:
SUNRPC: Zero rpc_gss_wire_cred at svcauth_gss_decode_credbody() entry
svcauth_gss_decode_credbody() writes the caller's rpc_gss_wire_cred field by field and assigns gc_ctx.len only on the success tail. The caller storage is svcdata->clcred, which lives in the per-svc_rqst gss_svc_data and is reused across requests. Early decode failures leave partially decoded state mixed with residue from the prior request.
The trailing body_len tightness check is the sharpest case: xdr_stream_decode_opaque_inline() has already written gc_ctx.data with a borrowed inline pointer into the current request's XDR pages, but gc_ctx.len retains its prior value. Once the request pages are released the pooled clcred carries a dangling pointer paired with a stale length.
Zero the caller's rpc_gss_wire_cred at function entry so that every early-return path leaves a deterministic all-zero cred. On the trailing tightness-check path, gc_ctx.len is now zero instead of stale, which neuters length-driven consumers such as gss_svc_searchbyctx() that would otherwise walk the dangling data pointer.
{
"affected": [],
"aliases": [
"CVE-2026-93207"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-24T16:17:15Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Zero rpc_gss_wire_cred at svcauth_gss_decode_credbody() entry\n\nsvcauth_gss_decode_credbody() writes the caller\u0027s\nrpc_gss_wire_cred field by field and assigns gc_ctx.len only on\nthe success tail. The caller storage is svcdata-\u003eclcred, which\nlives in the per-svc_rqst gss_svc_data and is reused across\nrequests. Early decode failures leave partially decoded state\nmixed with residue from the prior request.\n\nThe trailing body_len tightness check is the sharpest case:\nxdr_stream_decode_opaque_inline() has already written gc_ctx.data\nwith a borrowed inline pointer into the current request\u0027s XDR\npages, but gc_ctx.len retains its prior value. Once the request\npages are released the pooled clcred carries a dangling pointer\npaired with a stale length.\n\nZero the caller\u0027s rpc_gss_wire_cred at function entry so that\nevery early-return path leaves a deterministic all-zero cred.\nOn the trailing tightness-check path, gc_ctx.len is now zero\ninstead of stale, which neuters length-driven consumers such as\ngss_svc_searchbyctx() that would otherwise walk the dangling\ndata pointer.",
"id": "GHSA-hcpq-g756-q7pv",
"modified": "2026-09-25T06:30:26Z",
"published": "2026-09-24T18:31:21Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93207"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0e18641708eaa8bc3c1ff338cd844aeadbd52bac"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0fa8a8acae57e6373962741d5b06d13f44aba6a9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/11539e8fcce0b0af062ae5fecf7b3676c2f7aeed"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/56b29d62017c7dd1718d060dd5b3a2ce61095d0c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e0778464049b0238f2915a40007a4154f86cf351"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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