CVE-2026-74701 (GCVE-0-2026-74701)
Vulnerability from cvelistv5
Published
2026-08-22 15:33
Modified
2026-08-25 05:41
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/openvswitch: check Ethernet header length in key_extract()
When a packet arrives on an ARPHRD_NONE device (e.g. TUN),
ovs_flow_key_extract() trusts the user-provided skb->protocol field: if
it is ETH_P_TEB, the packet is classified as MAC_PROTO_ETHERNET and
key_extract() is called without ensuring the skb has ETH_HLEN (14) bytes
of linear data. key_extract() unconditionally pulls 2 * ETH_ALEN bytes
for MAC addresses and parse_ethertype() pulls 2 more, either of which
triggers a kernel BUG in __skb_pull() when the linear area is too small.
kernel BUG at include/linux/skbuff.h:2848!
RIP: 0010:key_extract+0xa7e/0xd90 net/openvswitch/flow.c:933
ovs_flow_key_extract+0x419/0xa70
ovs_vport_receive+0x222/0x390
netdev_frame_hook+0x3e0/0x630
tun_get_user+0x2d0c/0x38e0
Fixed by calling check_header() in key_extract() before accessing the
Ethernet header.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 217ac77a3c2524d999730b2a80b61fcc2d0f734a Version: 217ac77a3c2524d999730b2a80b61fcc2d0f734a Version: 217ac77a3c2524d999730b2a80b61fcc2d0f734a Version: 217ac77a3c2524d999730b2a80b61fcc2d0f734a Version: 217ac77a3c2524d999730b2a80b61fcc2d0f734a Version: 217ac77a3c2524d999730b2a80b61fcc2d0f734a Version: 217ac77a3c2524d999730b2a80b61fcc2d0f734a Version: 217ac77a3c2524d999730b2a80b61fcc2d0f734a |
||
{
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/openvswitch: check Ethernet header length in key_extract()\n\nWhen a packet arrives on an ARPHRD_NONE device (e.g. TUN),\novs_flow_key_extract() trusts the user-provided skb-\u003eprotocol field: if\nit is ETH_P_TEB, the packet is classified as MAC_PROTO_ETHERNET and\nkey_extract() is called without ensuring the skb has ETH_HLEN (14) bytes\nof linear data. key_extract() unconditionally pulls 2 * ETH_ALEN bytes\nfor MAC addresses and parse_ethertype() pulls 2 more, either of which\ntriggers a kernel BUG in __skb_pull() when the linear area is too small.\n\n kernel BUG at include/linux/skbuff.h:2848!\n RIP: 0010:key_extract+0xa7e/0xd90 net/openvswitch/flow.c:933\n ovs_flow_key_extract+0x419/0xa70\n ovs_vport_receive+0x222/0x390\n netdev_frame_hook+0x3e0/0x630\n tun_get_user+0x2d0c/0x38e0\n\nFixed by calling check_header() in key_extract() before accessing the\nEthernet header."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The crash is reached when a crafted skb is processed in ovs_flow_key_extract() via ovs_vport_receive(); the documented reproducer injects it through tun_get_user() (write to a TUN fd), and the alternate path is OVS_PACKET_CMD_EXECUTE netlink\u2014both require local syscall access, not remote packet delivery.\nAC:L - The attacker fully controls skb length, skb-\u003eprotocol (ETH_P_TEB), and linear versus fragmented layout; sending a sub-14-byte payload with ETH_P_TEB on an ARPHRD_NONE OVS port deterministically reaches key_extract() and triggers __skb_pull() BUG() without races or special heap layout.\nPR:L - Attaching an ARPHRD_NONE netdev to an OVS datapath and using OVS_PACKET_CMD_EXECUTE require CAP_NET_ADMIN (GENL_UNS_ADMIN_PERM, netnsok); CAP_NET_ADMIN is obtainable inside an unprivileged user+network namespace, and TUN injection likewise requires CAP_NET_ADMIN or a TUN fd granted by a privileged setup.\nUI:N - No victim interaction is required; once OVS bridges an ARPHRD_NONE port (e.g. TUN), the attacker triggers the bug by injecting a single malformed packet via write() or netlink without any other user action.\nS:U - Impact is a kernel BUG/panic in the same kernel security authority as the attacker; this is not a VM escape, IOMMU bypass, or cross-namespace privilege boundary crossing.\nC:H - Before the BUG, key_extract() calls ether_addr_copy() and parse_ethertype() on skb-\u003edata without validating ETH_HLEN, performing out-of-bounds reads of kernel skb buffer memory beyond the actual packet payload.\nI:H - Unchecked __skb_pull() on an undersized skb corrupts skb-\u003edata and skb-\u003elen metadata; this memory corruption of kernel packet state can be leveraged for further integrity violations beyond a simple controlled crash.\nA:H - The flaw triggers kernel BUG() at __skb_pull() in include/linux/skbuff.h, producing a kernel oops/panic and denying all system availability on affected hosts running Open vSwitch with ARPHRD_NONE ports."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:41:43.778Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/e85278afd4890dd190ba3c7a1b1a712b801c9fe1"
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{
"url": "https://git.kernel.org/stable/c/81f9b09f0ea3ba9ab966dd17e9f32625a14555e9"
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{
"url": "https://git.kernel.org/stable/c/d8bea341b183190ce6c055ab0e64ab78eb9a7290"
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{
"url": "https://git.kernel.org/stable/c/0b60b55652ba772b173dddc63f3851e1d2dd5927"
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{
"url": "https://git.kernel.org/stable/c/a8139285c8925efe59af28a9169bb2fda91bff15"
},
{
"url": "https://git.kernel.org/stable/c/9b8cfbb58b85bfa7a78fac47fdc77396cd01f699"
},
{
"url": "https://git.kernel.org/stable/c/cf6f8b29befb92173659bcef6a441d274947bfae"
}
],
"title": "net/openvswitch: check Ethernet header length in key_extract()",
"x_generator": {
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}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74701",
"datePublished": "2026-08-22T15:33:01.585Z",
"dateReserved": "2026-08-15T05:44:03.927Z",
"dateUpdated": "2026-08-25T05:41:43.778Z",
"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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