CriticalFix available
vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
Type: advisorySources: OSV
In the Linux kernel, the following vulnerability has been resolved: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu() skb_tunnel_check_pmtu() can change skb->head. Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF. Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c. Found by Sashiko.
- Products
- Kernel
- Affected versions
- Not specified
- Fixed versions
- 5.10.259, 5.15.210, 6.1.176, 6.12.93, 6.18.35, 6.6.143, 7.0.12
- CVEs
- CVE-2026-63993
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 03:49 UTC · Revision 1
Source evidence
vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()
core-osv · Original sourcePublished 19 Jul 2026, 14:56 UTC
In the Linux kernel, the following vulnerability has been resolved: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu() skb_tunnel_check_pmtu() can change skb->head. Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF. Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c. Found by Sashiko.
osv:CVE-2026-63993
Kernel
Fixed versions: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35, 7.0.12
Complete source record
{
"id": "bb698197262372de26ffb37ab91346d141470a29448619761ce80842a4215ba9",
"url": "https://osv.dev/vulnerability/CVE-2026-63993",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()",
"summary": "In the Linux kernel, the following vulnerability has been resolved: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu() skb_tunnel_check_pmtu() can change skb->head. Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF. Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c. Found by Sashiko.",
"evidence": "osv:CVE-2026-63993",
"products": [
{
"name": {
"value": "Kernel",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "5.10.259",
"evidence": "/affected/1/ranges"
},
{
"value": "5.15.210",
"evidence": "/affected/1/ranges"
},
{
"value": "6.1.176",
"evidence": "/affected/1/ranges"
},
{
"value": "6.6.143",
"evidence": "/affected/1/ranges"
},
{
"value": "6.12.93",
"evidence": "/affected/1/ranges"
},
{
"value": "6.18.35",
"evidence": "/affected/1/ranges"
},
{
"value": "7.0.12",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
}
],
"severity": "critical",
"structured": {
"id": "CVE-2026-63993",
"aliases": [
"CVE-2026-63993"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"type": "GIT",
"events": [
{
"introduced": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f"
},
{
"fixed": "6b8bfce9d2f774d2c2243e0248e03efb99bba6c0"
},
{
"fixed": "9257f56ac47ef1976bcd056cf986a9988eeec67a"
},
{
"fixed": "8d435d68d71fb875876b722f4136caf74f2f48bd"
},
{
"fixed": "dc3bfa050f873371e745bdf478b1f5b738e5733d"
},
{
"fixed": "609e63312c29aad18026a1d3222e123d4b6b0feb"
},
{
"fixed": "5303925e360527243b46a440a04667826bbc72b7"
},
{
"fixed": "a493efd4336cf19122ae0e4cbb3d31b32d70deea"
},
{
"fixed": "7d9ef0cb271555d8cf39fefe6c981e1493b25ecf"
}
]
}
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63993.json"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "5.9.0"
},
{
"fixed": "5.10.259"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "5.11.0"
},
{
"fixed": "5.15.210"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "5.16.0"
},
{
"fixed": "6.1.176"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "6.2.0"
},
{
"fixed": "6.6.143"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "6.7.0"
},
{
"fixed": "6.12.93"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "6.13.0"
},
{
"fixed": "6.18.35"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "6.19.0"
},
{
"fixed": "7.0.12"
}
]
}
],
"package": {
"name": "Kernel",
"ecosystem": "Linux"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63993.json"
}
}
],
"modified": "2026-10-28T02:30:32.823372643Z",
"provider": "osv",
"references": [
"https://git.kernel.org/stable/c/5303925e360527243b46a440a04667826bbc72b7",
"https://git.kernel.org/stable/c/609e63312c29aad18026a1d3222e123d4b6b0feb",
"https://git.kernel.org/stable/c/6b8bfce9d2f774d2c2243e0248e03efb99bba6c0",
"https://git.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecf",
"https://git.kernel.org/stable/c/8d435d68d71fb875876b722f4136caf74f2f48bd",
"https://git.kernel.org/stable/c/9257f56ac47ef1976bcd056cf986a9988eeec67a",
"https://git.kernel.org/stable/c/a493efd4336cf19122ae0e4cbb3d31b32d70deea",
"https://git.kernel.org/stable/c/dc3bfa050f873371e745bdf478b1f5b738e5733d",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63993.json",
"https://nvd.nist.gov/vuln/detail/CVE-2026-63993",
"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
],
"provider_metadata": {
"cna_assigner": "Linux",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63993.json"
}
},
"related_cves": [
{
"value": "CVE-2026-63993",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 500100,
"published_at": "2026-07-19T14:56:13.218+00:00"
}