CVE-2026-74492 (GCVE-0-2026-74492)
Vulnerability from cvelistv5 – Published: 2026-08-15 12:27 – Updated: 2026-10-16 19:05
VLAI
EPSS
VEX
Title
netfilter: ipset: do not update comments from kernel-side hash adds
Summary
In 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.
Severity
8.4 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 18:58 UTC
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
f66ee0410b1c3481ee75e5db9b34547b4d582465 , < 6f13f4d52d06986c18f12e8bffaab944dd27ceab
(git)
Affected: f66ee0410b1c3481ee75e5db9b34547b4d582465 , < f9d6cabff1fca010562dcdb0d22b296bdca3ba5a (git) Affected: f66ee0410b1c3481ee75e5db9b34547b4d582465 , < 16bfa7be2d76ca1e0aacfa363482e1bf8ab5042a (git) Affected: f66ee0410b1c3481ee75e5db9b34547b4d582465 , < 661ff9c0cfbe07f8eed920dde9f7781491738207 (git) Affected: f66ee0410b1c3481ee75e5db9b34547b4d582465 , < c710e9bf38e4e71a8db85d26a0f70c0674664207 (git) Affected: f66ee0410b1c3481ee75e5db9b34547b4d582465 , < 4ae701848e4ba9e9713375fb7d82218cbd309da2 (git) Affected: f66ee0410b1c3481ee75e5db9b34547b4d582465 , < 77dbb248a5cc7a5270cd37bbb0b635bf059a872a (git) Affected: f66ee0410b1c3481ee75e5db9b34547b4d582465 , < f30415929be8aeb002d557c8d3f7ab2d2188003a (git) Affected: 5dd9488ae41070b69d2f4acb580f77db5705f9ca (git) Affected: a469bab3386aebff33c59506f3a95e35b91118fd (git) Affected: 5.4.24 , < 5.5 (semver) Affected: 5.5.8 , < 5.6 (semver) |
guessed | |
| Linux | Linux |
Affected:
5.6
Unaffected: 0 , < 5.6 (semver) Unaffected: 5.10.265 , ≤ 5.10.* (semver) Unaffected: 5.15.216 , ≤ 5.15.* (semver) Unaffected: 6.1.183 , ≤ 6.1.* (semver) Unaffected: 6.6.151 , ≤ 6.6.* (semver) Unaffected: 6.12.103 , ≤ 6.12.* (semver) Unaffected: 6.18.44 , ≤ 6.18.* (semver) Unaffected: 7.1.8 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
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"value": "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": "CVE-2026-74492",
"lastModified": "2026-10-16T20:17:32.110",
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"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
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"options": [
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},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T18:58:08.112220Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-08-15T13:17:54.120",
"references": [
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},
{
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},
{
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{
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"url": "https://git.kernel.org/stable/c/c710e9bf38e4e71a8db85d26a0f70c0674664207"
},
{
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},
{
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"url": "https://git.kernel.org/stable/c/f9d6cabff1fca010562dcdb0d22b296bdca3ba5a"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-10-30T00:27:55+00:00",
"cve": "CVE-2026-74492",
"id": "CVE-2026-74492",
"initial_release_date": "2026-08-15T00:00:00+00:00",
"product_status:known_affected": "248",
"product_status:known_not_affected": "28",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: netfilter: ipset: do not update comments from kernel-side hash adds",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74492.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-74492",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T18:58:08.112220Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-10-16T18:58:09.007Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/netfilter/ipset/ip_set_hash_gen.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"status": "affected",
"version": "f66ee0410b1c3481ee75e5db9b34547b4d582465",
"versionType": "git"
},
{
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{
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{
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{
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{
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{
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{
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"programFiles": [
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],
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"vendor": "Linux",
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},
{
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},
{
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"version": "5.10.265",
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},
{
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"status": "unaffected",
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},
{
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"version": "6.1.183",
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{
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},
{
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"status": "unaffected",
"version": "6.12.103",
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{
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"version": "6.18.44",
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},
{
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"status": "unaffected",
"version": "7.1.8",
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},
{
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"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
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],
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"descriptions": [
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"value": "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."
}
],
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"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
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"value": "AV:L - The bug is reached via the netfilter xt_SET packet path (set_target_* -\u003e ip_set_add -\u003e kadt -\u003e mtype_add) during skb processing in iptables hooks; kernel CNA guidance treats netfilter/ipset as Local even when triggering packets arrive from the network.\nAC:L - An attacker can drive both sides of the resize race by filling a comment-enabled hash set and concurrently sending packets that hit SET --add-set --exist while mtype_resize() copies entries, making the shared-comment UAF window repeatable rather than dependent on uncontrollable timing.\nPR:N - Exploitation requires only sending traffic that matches an already-installed SET --exist rule on a comment-enabled ipset during resize; no local account or CAP_NET_ADMIN is needed, though unprivileged user namespaces can also obtain CAP_NET_ADMIN to configure the full attack chain.\nUI:N - Triggering is fully automatic through netfilter packet handling once the vulnerable ipset/iptables configuration exists; the attacker does not need the victim to click, mount, or perform any deliberate action beyond ordinary packet delivery.\nS:U - The flaw corrupts kernel heap memory and can yield host privilege escalation, but it does not cross a distinct security authority such as a VM/host, container/host, or IOMMU boundary; impact remains within the same kernel security domain.\nC:H - Packet-side mtype_add() frees a shared ip_set_comment_rcu during resize, leaving duplicate entries with dangling pointers; backlog replay calls ip_set_init_comment() and strlen() on freed kmalloc memory, a classic UAF that can disclose arbitrary kernel data with heap grooming.\nI:H - The UAF over RCU-freed comment objects lets an attacker reclaim and control freed slab memory, providing a standard path to arbitrary kernel writes, metadata corruption, and control-flow hijack rather than a bounded or crash-only integrity effect.\nA:H - Stale comment pointer dereference during resize backlog replay can immediately kernel-oops/panic the host, and the underlying UAF heap corruption can crash or hang the system even when full exploitation is not attempted."
}
]
}
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},
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}
],
"title": "netfilter: ipset: do not update comments from kernel-side hash adds",
"x_generator": {
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}
}
},
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"dateReserved": "2026-08-15T05:44:03.906Z",
"dateUpdated": "2026-10-16T19:05:49.918Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
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}
}
}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.