Vulnerability-Lookup

GHSA-WF82-H5XG-M662

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-19 18:32

Details

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.

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-68123"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:19:57Z",
    "severity": "CRITICAL"
  },
  "details": "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.",
  "id": "GHSA-wf82-h5xg-m662",
  "modified": "2026-08-19T18:32:05Z",
  "published": "2026-08-10T15:33:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68123"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/100a23b1613e9218e0af654ef102352c713f0263"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2623c48cc3a8da9a1886fd8f65c0e348f4406fd6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4032f8ed10fcb84d41c508dfb04be96589f78dfe"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/50a6a85f3d6b1d22d8436848606cdef5d2c490b4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e211b081901ffca76674082c73eeaed53524c369"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ea85dbcbe8d4056ecb54352f97743d138ea4c407"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-68123 (GCVE-0-2026-68123)

Vulnerability from cvelistv5 – Published: 2026-08-10 11:58 – Updated: 2026-08-19 16:29

Title

openvswitch: fix GSO userspace truncation underflow

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.

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

8 references

URL	Tags
https://git.kernel.org/stable/c/50a6a85f3d6b1d22d…
https://git.kernel.org/stable/c/2623c48cc3a8da9a1…
https://git.kernel.org/stable/c/e211b081901ffca76…
https://git.kernel.org/stable/c/a16eaaf7c0b0ccdef…
https://git.kernel.org/stable/c/fbfa3ad2ad6f3a562…
https://git.kernel.org/stable/c/100a23b1613e9218e…
https://git.kernel.org/stable/c/ea85dbcbe8d4056ec…
https://git.kernel.org/stable/c/4032f8ed10fcb84d4…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 , < 50a6a85f3d6b1d22d8436848606cdef5d2c490b4 (git) Affected: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 , < 2623c48cc3a8da9a1886fd8f65c0e348f4406fd6 (git) Affected: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 , < e211b081901ffca76674082c73eeaed53524c369 (git) Affected: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 , < a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855 (git) Affected: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 , < fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc (git) Affected: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 , < 100a23b1613e9218e0af654ef102352c713f0263 (git) Affected: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 , < ea85dbcbe8d4056ecb54352f97743d138ea4c407 (git) Affected: f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 , < 4032f8ed10fcb84d41c508dfb04be96589f78dfe (git)
Linux	Linux	Affected: 4.8 Unaffected: 0 , < 4.8 (semver) Unaffected: 5.10.265 , ≤ 5.10.* (semver) Unaffected: 5.15.216 , ≤ 5.15.* (semver) Unaffected: 6.1.183 , ≤ 6.1.* (semver) Unaffected: 6.6.148 , ≤ 6.6.* (semver) Unaffected: 6.12.101 , ≤ 6.12.* (semver) Unaffected: 6.18.42 , ≤ 6.18.* (semver) Unaffected: 7.1.6 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "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"
            },
            {
              "lessThan": "2623c48cc3a8da9a1886fd8f65c0e348f4406fd6",
              "status": "affected",
              "version": "f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1",
              "versionType": "git"
            },
            {
              "lessThan": "a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855",
              "status": "affected",
              "version": "f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1",
              "versionType": "git"
            },
            {
              "lessThan": "fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc",
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              "status": "affected",
              "version": "f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1",
              "versionType": "git"
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            "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",
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            },
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              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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                },
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                },
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                  "versionStartIncluding": "4.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.42",
                  "versionStartIncluding": "4.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "4.8",
                  "vulnerable": true
                },
                {
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                  "vulnerable": true
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            "baseSeverity": "CRITICAL",
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              "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."
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      "providerMetadata": {
        "dateUpdated": "2026-08-19T16:29:34.391Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/4032f8ed10fcb84d41c508dfb04be96589f78dfe"
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      "title": "openvswitch: fix GSO userspace truncation underflow",
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  "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"
  },
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  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-WF82-H5XG-M662

CVE-2026-68123 (GCVE-0-2026-68123)

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