GHSA-H46J-5F2W-JJQ4
Vulnerability from github – Published: 2026-08-17 06:33 – Updated: 2026-08-25 06:31In the Linux kernel, the following vulnerability has been resolved:
netfilter: nft_payload: fix mask build for partial field offload
nft_payload_offload_mask() builds the offload match mask for a payload expression that covers only part of a header field. For a partial IPv6 address match (field_len = 16, priv_len = 1) that shift is 1 << 120, which is undefined on the 32-bit int operand. It also trims only one word, so the remaining words stay 0xffffffff (and when priv_len is a multiple of 4 the trim is skipped entirely), leaving the mask covering more bytes than the rule matches.
UBSAN: shift-out-of-bounds in net/netfilter/nft_payload.c:278:20 shift exponent 120 is too large for 32-bit type 'int' ...
The match is byte-granular and struct nft_data is zero-initialised, so the correct mask is simply the first priv_len bytes set to 0xff. Set those bytes directly and drop the word/shift trimming; this removes the undefined shift and no longer over-masks the trailing bytes.
{
"affected": [],
"aliases": [
"CVE-2026-74579"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-17T06:19:56Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_payload: fix mask build for partial field offload\n\nnft_payload_offload_mask() builds the offload match mask for a payload\nexpression that covers only part of a header field. For a partial IPv6\naddress match (field_len = 16, priv_len = 1) that shift is 1 \u003c\u003c 120, which\nis undefined on the 32-bit int operand. It also trims only one word, so\nthe remaining words stay 0xffffffff (and when priv_len is a multiple of 4\nthe trim is skipped entirely), leaving the mask covering more bytes than\nthe rule matches.\n\n UBSAN: shift-out-of-bounds in net/netfilter/nft_payload.c:278:20\n shift exponent 120 is too large for 32-bit type \u0027int\u0027\n ...\n\nThe match is byte-granular and struct nft_data is zero-initialised, so the\ncorrect mask is simply the first priv_len bytes set to 0xff. Set those\nbytes directly and drop the word/shift trimming; this removes the undefined\nshift and no longer over-masks the trailing bytes.",
"id": "GHSA-h46j-5f2w-jjq4",
"modified": "2026-08-25T06:31:17Z",
"published": "2026-08-17T06:33:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74579"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/16b553c46e347bc9de9946c4960654d5884a86de"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/363c3a84a946d53e5e121c9f47c7c2b7d228c46b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/39e88f28fb32bf02bd4b525c24c842c9cff5663d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3ee7b3f813b11f28cd6efdf7f24d64b5a7fd4dc7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/630295d5bba1d0e0f494cc459452eb0a0058c545"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8720df4504e0ed1781a702f65251bd47b3534d5e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a375d8ace807767f29f276b681b6324c74929b1d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b19b5d2e042c294e2cc1c908dc598f9d64015396"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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