CVE-2026-68123 (GCVE-0-2026-68123)
Vulnerability from cvelistv5
Published
2026-08-10 11:58
Modified
2026-08-19 16:29
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
openvswitch: fix GSO userspace truncation underflow
OVS_ACTION_ATTR_TRUNC currently stores a delta from the original skb
length in OVS_CB(skb)->cutlen. When a later userspace action segments a
GSO skb, queue_gso_packets() reuses that delta for each smaller segment.
A segment can then reach queue_userspace_packet() with cutlen greater
than skb->len, underflowing the length passed to skb_zerocopy().
Store the maximum preserved length instead and bound each consumer
against the current skb length. Use U32_MAX as the no-truncation
sentinel so the value remains valid if skb geometry changes before a
consumer handles it.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 Version: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 Version: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 Version: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 Version: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 Version: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 Version: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 Version: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/openvswitch/actions.c",
"net/openvswitch/datapath.c",
"net/openvswitch/datapath.h",
"net/openvswitch/vport.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
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"status": "affected",
"version": "f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1",
"versionType": "git"
},
{
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"status": "affected",
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},
{
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"status": "affected",
"version": "f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1",
"versionType": "git"
},
{
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"versionType": "git"
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{
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"product": "Linux",
"programFiles": [
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"net/openvswitch/datapath.c",
"net/openvswitch/datapath.h",
"net/openvswitch/vport.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.8"
},
{
"lessThan": "4.8",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.265",
"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": "5.10.265",
"versionStartIncluding": "4.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.216",
"versionStartIncluding": "4.8",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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{
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
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},
{
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},
{
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"versionStartIncluding": "4.8",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: fix GSO userspace truncation underflow\n\nOVS_ACTION_ATTR_TRUNC currently stores a delta from the original skb\nlength in OVS_CB(skb)-\u003ecutlen. When a later userspace action segments a\nGSO skb, queue_gso_packets() reuses that delta for each smaller segment.\nA segment can then reach queue_userspace_packet() with cutlen greater\nthan skb-\u003elen, underflowing the length passed to skb_zerocopy().\n\nStore the maximum preserved length instead and bound each consumer\nagainst the current skb length. Use U32_MAX as the no-truncation\nsentinel so the value remains valid if skb geometry changes before a\nconsumer handles it."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - Ingress packets reach ovs_vport_receive() through netdev rx_handlers or tunnel vports; GRO-coalesced GSO skbs from remote senders traverse this path into queue_gso_packets(), so the underflow is reachable from the network without physical access.\nAC:L - The attacker chooses truncation max_len relative to GSO super-skb size and sends traffic that GRO segments predictably; no timing race or fragile heap layout is required to make cutlen exceed a child segment length after __skb_gso_segment().\nPR:N - In multi-tenant cloud/OVN deployments, a remote VM or container can send crafted GSO traffic into the host OVS datapath to hit provider-installed TRUNC+USERSPACE sampling flows without possessing any Linux capabilities on the host.\nUI:N - Triggering the flaw requires only network traffic matching existing OVS flow actions; no victim login, file open, mount, or other interactive step is needed.\nS:U - Impact is kernel memory corruption and crash/escalation within the host kernel security domain; it does not cross a guest-to-hypervisor, VM, or hardware IOMMU trust boundary by itself.\nC:H - Unsigned underflow makes skb-\u003elen-cutlen enormous for skb_zerocopy()/skb_copy_bits(), enabling out-of-bounds reads from the source skb and adjacent slab data, i.e., an exploitable information-disclosure primitive.\nI:H - The same underflowed length can expand destination skbs via skb_len_add()/nlattr sizing, corrupting kernel heap metadata and yielding a write primitive suitable for control-flow hijacking.\nA:H - The miscopied lengths can BUG the skb helpers or cause immediate kernel oops/panic during zerocopy/trim handling, and corrupted metadata can crash the system even if exploitation is not completed."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-19T16:29:34.391Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/50a6a85f3d6b1d22d8436848606cdef5d2c490b4"
},
{
"url": "https://git.kernel.org/stable/c/2623c48cc3a8da9a1886fd8f65c0e348f4406fd6"
},
{
"url": "https://git.kernel.org/stable/c/e211b081901ffca76674082c73eeaed53524c369"
},
{
"url": "https://git.kernel.org/stable/c/a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855"
},
{
"url": "https://git.kernel.org/stable/c/fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc"
},
{
"url": "https://git.kernel.org/stable/c/100a23b1613e9218e0af654ef102352c713f0263"
},
{
"url": "https://git.kernel.org/stable/c/ea85dbcbe8d4056ecb54352f97743d138ea4c407"
},
{
"url": "https://git.kernel.org/stable/c/4032f8ed10fcb84d41c508dfb04be96589f78dfe"
}
],
"title": "openvswitch: fix GSO userspace truncation underflow",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-68123",
"datePublished": "2026-08-10T11:58:43.727Z",
"dateReserved": "2026-07-30T09:28:09.369Z",
"dateUpdated": "2026-08-19T16:29:34.391Z",
"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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