cve-2026-63994
CRITICAL CVSS 9.8 opencve
Description
In the Linux kernel, the following vulnerability has been resolved: tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]() Sashiko found that iptunnel_pmtud_build_icmp() and iptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr() before an skb_cow() call which can reallocate skb->head. Fix this possible UAF by initializing the local variables after the skb_cow() call. Remove skb_reset_network_header() calls which were not needed.
Timeline
- Published
- 2026-07-19 16:17 UTC
- Last Modified
- 2026-07-30
CVSS Details
CVSS details not available.
Affected Products
No product information available.
Weaknesses (CWE)
CVSS metrics
| Version | Base | Severity | Vector | Exploitability | Impact | Source |
|---|---|---|---|---|---|---|
| 3.1 | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
mitre | ||
| 3.1 | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
nvd | ||
| 3.1 | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
opencve | ||
| 3.1 | 7.0 | HIGH | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H |
redhat |
References
No references available.
Linked Vulnerabilities
{
"advisories": [
{
"id": "USN-8593-1",
"source": "usn",
"title": "Linux kernel vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8593-1"
},
{
"id": "USN-8603-1",
"source": "usn",
"title": "Linux kernel (Azure) vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8603-1"
},
{
"id": "USN-8618-1",
"source": "usn",
"title": "Linux kernel vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8618-1"
},
{
"id": "USN-8663-1",
"source": "usn",
"title": "Linux kernel (NVIDIA) vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8663-1"
},
{
"id": "USN-8664-1",
"source": "usn",
"title": "Linux kernel (NVIDIA BaseOS) vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8664-1"
},
{
"id": "USN-8728-1",
"source": "usn",
"title": "Linux kernel (GCP) vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8728-1"
},
{
"id": "USN-8781-1",
"source": "usn",
"title": "Linux kernel (NVIDIA Tegra) vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8781-1"
},
{
"id": "USN-8728-2",
"source": "usn",
"title": "Linux kernel (Azure) vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8728-2"
},
{
"id": "USN-8817-1",
"source": "usn",
"title": "Linux kernel vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8817-1"
},
{
"id": "USN-8818-1",
"source": "usn",
"title": "Linux kernel vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8818-1"
},
{
"id": "USN-8818-2",
"source": "usn",
"title": "Linux kernel (IBM) vulnerabilities",
"url": "https://ubuntu.com/security/notices/USN-8818-2"
}
],
"cve": "CVE-2026-63994",
"enrichment": {
"affected": [
{
"configurations": [
{
"platform": null,
"status": "affected",
"versions": {
"scheme": "code_commit",
"value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,95b6d772bfe788331d9742d73eaa12e113b2adc4)"
}
},
{
"platform": null,
"status": "affected",
"versions": {
"scheme": "code_commit",
"value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,7254aef4d1a7e18e887af9010e2f2dc34806789b)"
}
},
{
"platform": null,
"status": "affected",
"versions": {
"scheme": "code_commit",
"value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,bf8b3f34c37c162357138e7c0942723b8b94fed1)"
}
},
{
"platform": null,
"status": "affected",
"versions": {
"scheme": "code_commit",
"value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,76cd9398a0470257ab765bdf5f358a2af2e17934)"
}
},
{
"platform": null,
"status": "affected",
"versions": {
"scheme": "code_commit",
"value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,50750d86a2e5266aba0c295483b3397843198b11)"
}
},
{
"platform": null,
"status": "affected",
"versions": {
"scheme": "code_commit",
"value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,6dff77899b9e9fe5d854abda3a98ad04e7229ef7)"
}
},
{
"platform": null,
"status": "affected",
"versions": {
"scheme": "code_commit",
"value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,f3f204541f280a6ecb04503a0d6794d93990ca43)"
}
},
{
"platform": null,
"status": "affected",
"versions": {
"scheme": "code_commit",
"value": "[4cb47a8644cc9eb8ec81190a50e79e6530d0297f,b4bc94353050b1fa7b702bd4c6600710dd926cff)"
}
}
],
"enrichment": {
"confidence": 99.0,
"confidence_source": "inferred",
"scores": [
{
"score": 99.0,
"source": "inferred"
},
{
"score": 100.0,
"source": "matching"
}
]
},
"original": {
"product": "Linux",
"source": "cna",
"vendor": "Linux"
},
"product": "linux_kernel",
"vendor": "linux"
},
{
"configurations": [
{
"platform": null,
"status": "affected",
"versions": {
"scheme": "generic",
"value": "5.9"
}
},
{
"platform": null,
"status": "unaffected",
"versions": {
"scheme": "semver",
"value": "[0,5.9)"
}
},
{
"platform": null,
"status": "unaffected",
"versions": {
"scheme": "semver",
"value": "[5.10.259,5.11.0)"
}
},
{
"platform": null,
"status": "unaffected",
"versions": {
"scheme": "semver",
"value": "[5.15.210,5.16.0)"
}
},
{
"platform": null,
"status": "unaffected",
"versions": {
"scheme": "semver",
"value": "[6.1.176,6.2.0)"
}
},
{
"platform": null,
"status": "unaffected",
"versions": {
"scheme": "semver",
"value": "[6.6.143,6.7.0)"
}
},
{
"platform": null,
"status": "unaffected",
"versions": {
"scheme": "semver",
"value": "[6.12.93,6.13.0)"
}
},
{
"platform": null,
"status": "unaffected",
"versions": {
"scheme": "semver",
"value": "[6.18.35,6.19.0)"
}
},
{
"platform": null,
"status": "unaffected",
"versions": {
"scheme": "semver",
"value": "[7.0.12,7.1.0)"
}
},
{
"platform": null,
"status": "unaffected",
"versions": {
"scheme": "semver",
"value": "[7.1,*]"
}
}
],
"enrichment": {
"confidence": 99.0,
"confidence_source": "inferred",
"scores": [
{
"score": 99.0,
"source": "inferred"
},
{
"score": 100.0,
"source": "matching"
}
]
},
"original": {
"product": "Linux",
"source": "cna",
"vendor": "Linux"
},
"product": "linux_kernel",
"vendor": "linux"
}
],
"created": "2026-07-21T06:45:02.909498+00:00",
"updated": "2026-08-05T03:30:06.894826+00:00",
"vendors": [
"linux",
"linux$PRODUCT$linux_kernel"
]
},
"epss": {
"score": 0.00755
},
"mitre": {
"cpes": [
"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*"
],
"created": "2026-07-19T14:56:13.896000+00:00",
"description": "In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()\n\nSashiko found that iptunnel_pmtud_build_icmp() and\niptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr()\nbefore an skb_cow() call which can reallocate skb->head.\n\nFix this possible UAF by initializing the local variables\nafter the skb_cow() call.\n\nRemove skb_reset_network_header() calls which were not needed.",
"metrics": {
"cvssV2_0": {},
"cvssV3_0": {},
"cvssV3_1": {
"score": 9.8,
"vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
},
"cvssV4_0": {}
},
"mitre_repo_path": "cves/2026/63xxx/CVE-2026-63994.json",
"references": [
"https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11",
"https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7",
"https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b",
"https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934",
"https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4",
"https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff",
"https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1",
"https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43"
],
"title": "tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()",
"updated": "2026-08-05T12:37:58.389000+00:00",
"vendors": [
"linux",
"linux$PRODUCT$linux_kernel"
],
"weaknesses": []
},
"nvd": {
"cpes": [],
"created": "2026-07-19T16:17:38.943000+00:00",
"description": "In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()\n\nSashiko found that iptunnel_pmtud_build_icmp() and\niptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr()\nbefore an skb_cow() call which can reallocate skb->head.\n\nFix this possible UAF by initializing the local variables\nafter the skb_cow() call.\n\nRemove skb_reset_network_header() calls which were not needed.",
"metrics": {
"cvssV2_0": {},
"cvssV3_0": {},
"cvssV3_1": {
"score": 9.8,
"vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
},
"cvssV4_0": {}
},
"nvd_repo_path": "2026/CVE-2026-63994.json",
"references": [
"https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11",
"https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7",
"https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b",
"https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934",
"https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4",
"https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff",
"https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1",
"https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43"
],
"title": null,
"updated": "2026-07-30T14:51:11.223000+00:00",
"vendors": [],
"weaknesses": []
},
"opencve": {
"changes": [
{
"created": "2026-07-19T15:30:00+00:00",
"data": [
{
"details": {
"new": "In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()\n\nSashiko found that iptunnel_pmtud_build_icmp() and\niptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr()\nbefore an skb_cow() call which can reallocate skb->head.\n\nFix this possible UAF by initializing the local variables\nafter the skb_cow() call.\n\nRemove skb_reset_network_header() calls which were not needed.",
"old": null
},
"type": "description"
},
{
"details": {
"new": "tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()",
"old": null
},
"type": "title"
},
{
"details": [
"linux",
"linux$PRODUCT$linux_kernel"
],
"type": "first_time"
},
{
"details": {
"added": [
"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*"
],
"removed": []
},
"type": "cpes"
},
{
"details": {
"added": [
"linux",
"linux$PRODUCT$linux_kernel"
],
"removed": []
},
"type": "vendors"
},
{
"details": {
"added": [
"https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11",
"https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7",
"https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b",
"https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934",
"https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4",
"https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff",
"https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1",
"https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43"
],
"removed": []
},
"type": "references"
}
],
"id": "8ebea3e0-003b-4ac9-bfd6-4c6f375853a3"
},
{
"created": "2026-07-20T14:45:00+00:00",
"data": [
{
"details": {
"added": {
"cvssV3_1": {
"score": 9.8,
"vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
}
},
"removed": {},
"updated": {}
},
"type": "metrics"
}
],
"id": "e4ae0a50-9fab-4f50-b6d6-3940e65df071"
},
{
"created": "2026-07-22T00:15:00+00:00",
"data": [
{
"details": {
"added": [
"CWE-825"
],
"removed": []
},
"type": "weaknesses"
},
{
"details": {
"added": [
"https://lore.kernel.org/linux-cve-announce/2026071905-CVE-2026-63994-97bf@gregkh/T",
"https://nvd.nist.gov/vuln/detail/CVE-2026-63994",
"https://www.cve.org/CVERecord?id=CVE-2026-63994"
],
"removed": []
},
"type": "references"
},
{
"details": {
"added": {},
"removed": {},
"updated": {
"threat_severity": {
"new": "Important",
"old": null
}
}
},
"type": "metrics"
}
],
"id": "0f539da9-0f7a-43bd-8fb6-617bc2bd3215"
}
],
"cpes": {
"data": [
"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*"
],
"providers": [
"mitre"
]
},
"created": {
"data": "2026-07-19T00:00:00+00:00",
"provider": "redhat"
},
"description": {
"data": "In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()\n\nSashiko found that iptunnel_pmtud_build_icmp() and\niptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr()\nbefore an skb_cow() call which can reallocate skb->head.\n\nFix this possible UAF by initializing the local variables\nafter the skb_cow() call.\n\nRemove skb_reset_network_header() calls which were not needed.",
"provider": "mitre"
},
"metrics": {
"cvssV2_0": {
"data": {},
"provider": null
},
"cvssV3_0": {
"data": {},
"provider": null
},
"cvssV3_1": {
"data": {
"score": 9.8,
"vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
},
"provider": "mitre"
},
"cvssV4_0": {
"data": {},
"provider": null
},
"epss": {
"data": {
"score": 0.00755
},
"provider": "first"
},
"kev": {
"data": {},
"provider": null
},
"ssvc": {
"data": {},
"provider": null
},
"threat_severity": {
"data": "Important",
"provider": "redhat"
}
},
"references": {
"data": [
"https://git.kernel.org/stable/c/50750d86a2e5266aba0c295483b3397843198b11",
"https://git.kernel.org/stable/c/6dff77899b9e9fe5d854abda3a98ad04e7229ef7",
"https://git.kernel.org/stable/c/7254aef4d1a7e18e887af9010e2f2dc34806789b",
"https://git.kernel.org/stable/c/76cd9398a0470257ab765bdf5f358a2af2e17934",
"https://git.kernel.org/stable/c/95b6d772bfe788331d9742d73eaa12e113b2adc4",
"https://git.kernel.org/stable/c/b4bc94353050b1fa7b702bd4c6600710dd926cff",
"https://git.kernel.org/stable/c/bf8b3f34c37c162357138e7c0942723b8b94fed1",
"https://git.kernel.org/stable/c/f3f204541f280a6ecb04503a0d6794d93990ca43",
"https://lore.kernel.org/linux-cve-announce/2026071905-CVE-2026-63994-97bf@gregkh/T",
"https://nvd.nist.gov/vuln/detail/CVE-2026-63994",
"https://www.cve.org/CVERecord?id=CVE-2026-63994"
],
"providers": [
"mitre",
"nvd",
"redhat"
]
},
"title": {
"data": "tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()",
"provider": "mitre"
},
"updated": {
"data": "2026-07-21T06:45:02.909540+00:00",
"provider": "enrichment"
},
"vendors": {
"data": [
"linux",
"linux$PRODUCT$linux_kernel"
],
"providers": [
"mitre",
"enrichment"
]
},
"weaknesses": {
"data": [
"CWE-825"
],
"providers": [
"redhat"
]
}
},
"redhat": {
"cpes": [],
"created": "2026-07-19T00:00:00+00:00",
"description": "In the Linux kernel, the following vulnerability has been resolved:\ntunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()\nSashiko found that iptunnel_pmtud_build_icmp() and\niptunnel_pmtud_build_icmpv6() were caching ip_hdr() and ipv6_hdr()\nbefore an skb_cow() call which can reallocate skb->head.\nFix this possible UAF by initializing the local variables\nafter the skb_cow() call.\nRemove skb_reset_network_header() calls which were not needed.",
"metrics": {
"cvssV2_0": {},
"cvssV3_0": {},
"cvssV3_1": {
"score": 7.0,
"vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
},
"threat_severity": "Important"
},
"redhat_repo_path": "2026/CVE-2026-63994.json",
"references": [
"https://lore.kernel.org/linux-cve-announce/2026071905-CVE-2026-63994-97bf@gregkh/T",
"https://nvd.nist.gov/vuln/detail/CVE-2026-63994",
"https://www.cve.org/CVERecord?id=CVE-2026-63994"
],
"title": "kernel: tunnels: load network headers after skb_cow() in iptunnel_pmtud_build_icmp[v6]()",
"updated": "2026-07-19T00:00:00+00:00",
"vendors": [],
"weaknesses": [
"CWE-825"
]
}
}
Enrichment data
Aggregated bundle (all enrichments)