GHSA-J8FQ-XQCV-34C2
Vulnerability from github – Published: 2026-08-15 15:30 – Updated: 2026-08-19 18:32In the Linux kernel, the following vulnerability has been resolved:
netfilter: ipset: do not update comments from kernel-side hash adds
mtype_resize() copies comment pointers with memcpy(), not the comment objects themselves. During the window after an entry has been copied but before the table swap and backlog replay, the old table is still published for packet-side updates while the replacement-table entry already holds the same ip_set_comment_rcu pointer.
If xt_SET --add-set ... --exist hits that old entry in this window, mtype_add() calls ip_set_init_comment() even though packet-side adds carry no comment payload. That call frees the shared comment through the old entry, so the replacement-table entry now holds a stale pointer. When the queued add is replayed on the new table, mtype_add() calls ip_set_init_comment() again and strlen() dereferences the stale pointer.
Fix this in mtype_add() by skipping ip_set_init_comment() when ext->target marks a packet-side add. Userspace adds still update comments, while packet-side adds can no longer free comment storage shared with a resize copy.
{
"affected": [],
"aliases": [
"CVE-2026-74492"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-15T13:17:54Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ipset: do not update comments from kernel-side hash adds\n\nmtype_resize() copies comment pointers with memcpy(), not the comment\nobjects themselves. During the window after an entry has been copied but\nbefore the table swap and backlog replay, the old table is still\npublished for packet-side updates while the replacement-table entry\nalready holds the same ip_set_comment_rcu pointer.\n\nIf xt_SET --add-set ... --exist hits that old entry in this window,\nmtype_add() calls ip_set_init_comment() even though packet-side adds\ncarry no comment payload. That call frees the shared comment through the\nold entry, so the replacement-table entry now holds a stale pointer.\nWhen the queued add is replayed on the new table, mtype_add() calls\nip_set_init_comment() again and strlen() dereferences the stale pointer.\n\nFix this in mtype_add() by skipping ip_set_init_comment() when\next-\u003etarget marks a packet-side add. Userspace adds still update\ncomments, while packet-side adds can no longer free comment storage\nshared with a resize copy.",
"id": "GHSA-j8fq-xqcv-34c2",
"modified": "2026-08-19T18:32:28Z",
"published": "2026-08-15T15:30:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74492"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/16bfa7be2d76ca1e0aacfa363482e1bf8ab5042a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4ae701848e4ba9e9713375fb7d82218cbd309da2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/661ff9c0cfbe07f8eed920dde9f7781491738207"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/6f13f4d52d06986c18f12e8bffaab944dd27ceab"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/77dbb248a5cc7a5270cd37bbb0b635bf059a872a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c710e9bf38e4e71a8db85d26a0f70c0674664207"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f30415929be8aeb002d557c8d3f7ab2d2188003a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f9d6cabff1fca010562dcdb0d22b296bdca3ba5a"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Confirmed: The vulnerability has been validated from an analyst's perspective.
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- 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.
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