GHSA-959H-4FXQ-GQHJ
Vulnerability from github – Published: 2026-09-11 21:31 – Updated: 2026-09-14 15:32In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix ALIGN() overflow in symlink_data() error context loop
The check added by commit 7d9a7f1f96cd ("smb/client: fix possible infinite loop and oob read in symlink_data()") compared the post-ALIGN length against the remaining buffer, but ALIGN() itself can overflow: for ErrorDataLength near UINT32_MAX (e.g. 0xFFFFFFF9), ALIGN(x, 8) wraps to 0, so the subsequent bounds check passes, and the loop advances by zero bytes leaving 'p' pointing into stale data.
Fix by checking the raw ErrorDataLength against the remaining space before applying ALIGN(), then checking again after. Since raw_len is bounded by the buffer, raw_len + 7 cannot overflow, so the second check is an exact post-alignment bounds guard.
{
"affected": [],
"aliases": [
"CVE-2026-89634"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-11T20:19:49Z",
"severity": "CRITICAL"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix ALIGN() overflow in symlink_data() error context loop\n\nThe check added by commit 7d9a7f1f96cd (\"smb/client: fix possible\ninfinite loop and oob read in symlink_data()\") compared the post-ALIGN\nlength against the remaining buffer, but ALIGN() itself can overflow:\nfor ErrorDataLength near UINT32_MAX (e.g. 0xFFFFFFF9), ALIGN(x, 8)\nwraps to 0, so the subsequent bounds check passes, and the loop\nadvances by zero bytes leaving \u0027p\u0027 pointing into stale data.\n\nFix by checking the raw ErrorDataLength against the remaining space\nbefore applying ALIGN(), then checking again after. Since raw_len is\nbounded by the buffer, raw_len + 7 cannot overflow, so the second check\nis an exact post-alignment bounds guard.",
"id": "GHSA-959h-4fxq-gqhj",
"modified": "2026-09-14T15:32:32Z",
"published": "2026-09-11T21:31:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89634"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1f824f61d1df52392eaf0b74dfa5659d724fde30"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2b4a25baa0b936fef6915c0459925077b324ecaf"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/62656b024efc21c3230eade1a847f25871c3d2bb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/62a3025983c8c735a3c6fc85a59316f31b59af07"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/657372ba6ea50b4474d2a6a610097eae8cd1f3e9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b89d678f9eafcf8d74885983166ba26b40a04ea0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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