CVE-2026-64576 (GCVE-0-2026-64576)
Vulnerability from cvelistv5
Published
2026-08-05 08:09
Modified
2026-08-19 16:28
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
nexthop: initialize extack in nh_res_bucket_migrate()
nh_res_bucket_migrate() passes an uninitialized netlink_ext_ack to
call_nexthop_res_bucket_notifiers(). When
nh_notifier_res_bucket_info_init() fails (e.g. the kzalloc returns
-ENOMEM), the error is propagated back before any notifier sets
extack._msg, and the error path formats the stale pointer with
pr_err_ratelimited("%s\n", extack._msg). With CONFIG_INIT_STACK_NONE
this dereferences uninitialized stack memory:
Oops: general protection fault, probably for non-canonical address ...
KASAN: maybe wild-memory-access in range [...]
RIP: 0010:string (lib/vsprintf.c:730)
vsnprintf (lib/vsprintf.c:2945)
_printk (kernel/printk/printk.c:2504)
nh_res_bucket_migrate (net/ipv4/nexthop.c:1816)
nh_res_table_upkeep (net/ipv4/nexthop.c:1866)
rtm_new_nexthop (net/ipv4/nexthop.c:3323)
rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)
netlink_sendmsg (net/netlink/af_netlink.c:1900)
Kernel panic - not syncing: Fatal exception
Zero-initialize extack so _msg is NULL on error paths that never set it.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 7c37c7e00411b3d1e0c5292368317aca69d1f324 Version: 7c37c7e00411b3d1e0c5292368317aca69d1f324 Version: 7c37c7e00411b3d1e0c5292368317aca69d1f324 Version: 7c37c7e00411b3d1e0c5292368317aca69d1f324 Version: 7c37c7e00411b3d1e0c5292368317aca69d1f324 Version: 7c37c7e00411b3d1e0c5292368317aca69d1f324 Version: 7c37c7e00411b3d1e0c5292368317aca69d1f324 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/ipv4/nexthop.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"status": "affected",
"version": "7c37c7e00411b3d1e0c5292368317aca69d1f324",
"versionType": "git"
},
{
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"status": "affected",
"version": "7c37c7e00411b3d1e0c5292368317aca69d1f324",
"versionType": "git"
},
{
"lessThan": "c0936c131a71657afc635d0db2ab096d15d473e1",
"status": "affected",
"version": "7c37c7e00411b3d1e0c5292368317aca69d1f324",
"versionType": "git"
},
{
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"status": "affected",
"version": "7c37c7e00411b3d1e0c5292368317aca69d1f324",
"versionType": "git"
},
{
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"status": "affected",
"version": "7c37c7e00411b3d1e0c5292368317aca69d1f324",
"versionType": "git"
},
{
"lessThan": "18506d7263768d76ac8e057ba55a4d9da50aad66",
"status": "affected",
"version": "7c37c7e00411b3d1e0c5292368317aca69d1f324",
"versionType": "git"
},
{
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"status": "affected",
"version": "7c37c7e00411b3d1e0c5292368317aca69d1f324",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/ipv4/nexthop.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.13"
},
{
"lessThan": "5.13",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.148",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.216",
"versionStartIncluding": "5.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.183",
"versionStartIncluding": "5.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.148",
"versionStartIncluding": "5.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.101",
"versionStartIncluding": "5.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.42",
"versionStartIncluding": "5.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.6",
"versionStartIncluding": "5.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "5.13",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnexthop: initialize extack in nh_res_bucket_migrate()\n\nnh_res_bucket_migrate() passes an uninitialized netlink_ext_ack to\ncall_nexthop_res_bucket_notifiers(). When\nnh_notifier_res_bucket_info_init() fails (e.g. the kzalloc returns\n-ENOMEM), the error is propagated back before any notifier sets\nextack._msg, and the error path formats the stale pointer with\npr_err_ratelimited(\"%s\\n\", extack._msg). With CONFIG_INIT_STACK_NONE\nthis dereferences uninitialized stack memory:\n\n Oops: general protection fault, probably for non-canonical address ...\n KASAN: maybe wild-memory-access in range [...]\n RIP: 0010:string (lib/vsprintf.c:730)\n vsnprintf (lib/vsprintf.c:2945)\n _printk (kernel/printk/printk.c:2504)\n nh_res_bucket_migrate (net/ipv4/nexthop.c:1816)\n nh_res_table_upkeep (net/ipv4/nexthop.c:1866)\n rtm_new_nexthop (net/ipv4/nexthop.c:3323)\n rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n netlink_sendmsg (net/netlink/af_netlink.c:1900)\n Kernel panic - not syncing: Fatal exception\n\nZero-initialize extack so _msg is NULL on error paths that never set it."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.1,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - Triggered via local RTM_NEWNEXTHOP over rtnetlink (sendmsg \u2192 rtnetlink_rcv_msg \u2192 rtm_new_nexthop \u2192 nh_res_table_upkeep \u2192 nh_res_bucket_migrate), not by processing remote packets.\nAC:L - An attacker can create resilient nexthop groups, ensure notifiers are registered (e.g. VXLAN pernet init), force bucket migration, and induce the kzalloc -ENOMEM path; stack contents are groomable, with no attacker-independent condition required.\nPR:L - rtnetlink_rcv_msg requires CAP_NET_ADMIN via netlink_net_capable() against the socket netns user_ns, which an unprivileged user obtains with unshare -Urn, so privileges are Low not High.\nUI:N - The attacker issues the netlink nexthop configuration and triggers migration themselves; no victim action is required.\nS:U - Impact stays within the host kernel networking authority; this is a local DoS/disclosure bug, not a VM escape, IOMMU bypass, or other cross-boundary scope change.\nC:H - pr_err_ratelimited(\"%s\") dereferences an uninitialized extack._msg pointer as a C string, enabling an attacker-groomable wild kernel read into the log, consistent with treating unbounded wild/OOB reads as Confidentiality High.\nI:N - The defect only reads through the stale _msg pointer for printing; there is no write, free, or other memory-corruption integrity primitive.\nA:H - The wild %s dereference causes a general protection fault / KASAN wild-memory-access and kernel panic, as shown in the fix commit report, so Availability is High."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-19T16:28:57.222Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/eacd2e2117e8682f937967fda1022e7f1c22d91a"
},
{
"url": "https://git.kernel.org/stable/c/37bbd7e1d8df0bec3d187e961783e20c30533d2c"
},
{
"url": "https://git.kernel.org/stable/c/c0936c131a71657afc635d0db2ab096d15d473e1"
},
{
"url": "https://git.kernel.org/stable/c/3081702ea5aca0aeed9c1ade8eadf6cde8db6b7d"
},
{
"url": "https://git.kernel.org/stable/c/d536bf205c71f700f6de2086038c3e1d77724715"
},
{
"url": "https://git.kernel.org/stable/c/18506d7263768d76ac8e057ba55a4d9da50aad66"
},
{
"url": "https://git.kernel.org/stable/c/6347c5314cee49f364aaf2e40ff15415a57a116e"
}
],
"title": "nexthop: initialize extack in nh_res_bucket_migrate()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-64576",
"datePublished": "2026-08-05T08:09:32.529Z",
"dateReserved": "2026-07-19T15:36:31.798Z",
"dateUpdated": "2026-08-19T16:28:57.222Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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