GHSA-H46J-5F2W-JJQ4
Vulnerability from github – Published: 2026-08-17 06:33 – Updated: 2026-08-17 06:33In 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": null
},
"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": "2026-08-17T06:33:56Z",
"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/39e88f28fb32bf02bd4b525c24c842c9cff5663d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/630295d5bba1d0e0f494cc459452eb0a0058c545"
},
{
"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": []
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.