Vulnerability-Lookup

GHSA-86MR-R4JR-F66C

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-17 06:33

Details

In the Linux kernel, the following vulnerability has been resolved:

vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive().

udp_tunnel_sock_release() could set sk->sk_user_data to NULL while vxlan_gro_prepare_receive() is running.

Let's check if rcu_dereference_sk_user_data() is NULL after skb_gro_remcsum_init().

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-2026-74406"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:42Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive().\n\nudp_tunnel_sock_release() could set sk-\u003esk_user_data to NULL\nwhile vxlan_gro_prepare_receive() is running.\n\nLet\u0027s check if rcu_dereference_sk_user_data() is NULL after\nskb_gro_remcsum_init().",
  "id": "GHSA-86mr-r4jr-f66c",
  "modified": "2026-08-17T06:33:43Z",
  "published": "2026-08-15T06:32:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74406"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/08f40c0d23c67c3aa4224c3311e134999c721fb4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/30a45c0bffdd62350261e2f2689fdba426a33578"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4a8cde6f7281ea2c4c290f9ad9923b3631defceb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9c58c729d32e7cea5772cc44929c6cd61e5a31cd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ef44dac2a37f86eeae6b88ed10a6d60b35387dfd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f79c80f173fda9545b220c1f094b65fc06c252d0"
    }
  ],
  "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-2026-74406 (GCVE-0-2026-74406)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:59 – Updated: 2026-08-17 05:46

Title

vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive().

Summary

In the Linux kernel, the following vulnerability has been resolved: vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive(). udp_tunnel_sock_release() could set sk->sk_user_data to NULL while vxlan_gro_prepare_receive() is running. Let's check if rcu_dereference_sk_user_data() is NULL after skb_gro_remcsum_init().

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

6 references

URL	Tags
https://git.kernel.org/stable/c/9c58c729d32e7cea5…
https://git.kernel.org/stable/c/f79c80f173fda9545…
https://git.kernel.org/stable/c/08f40c0d23c67c3aa…
https://git.kernel.org/stable/c/4a8cde6f7281ea2c4…
https://git.kernel.org/stable/c/ef44dac2a37f86eea…
https://git.kernel.org/stable/c/30a45c0bffdd62350…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 5602c48cf87562c2f95b831d690631935e834295 , < 9c58c729d32e7cea5772cc44929c6cd61e5a31cd (git) Affected: 5602c48cf87562c2f95b831d690631935e834295 , < f79c80f173fda9545b220c1f094b65fc06c252d0 (git) Affected: 5602c48cf87562c2f95b831d690631935e834295 , < 08f40c0d23c67c3aa4224c3311e134999c721fb4 (git) Affected: 5602c48cf87562c2f95b831d690631935e834295 , < 4a8cde6f7281ea2c4c290f9ad9923b3631defceb (git) Affected: 5602c48cf87562c2f95b831d690631935e834295 , < ef44dac2a37f86eeae6b88ed10a6d60b35387dfd (git) Affected: 5602c48cf87562c2f95b831d690631935e834295 , < 30a45c0bffdd62350261e2f2689fdba426a33578 (git)
Linux	Linux	Affected: 4.7 Unaffected: 0 , < 4.7 (semver) Unaffected: 6.1.178 , ≤ 6.1.* (semver) Unaffected: 6.6.145 , ≤ 6.6.* (semver) Unaffected: 6.12.97 , ≤ 6.12.* (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/vxlan/vxlan_core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "lessThan": "9c58c729d32e7cea5772cc44929c6cd61e5a31cd",
              "status": "affected",
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              "versionType": "git"
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              "lessThan": "f79c80f173fda9545b220c1f094b65fc06c252d0",
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              "version": "5602c48cf87562c2f95b831d690631935e834295",
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              "versionType": "git"
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              "lessThan": "ef44dac2a37f86eeae6b88ed10a6d60b35387dfd",
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              "versionType": "git"
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              "version": "5602c48cf87562c2f95b831d690631935e834295",
              "versionType": "git"
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              "version": "4.7"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
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              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
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            {
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              "status": "unaffected",
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              "versionType": "semver"
            },
            {
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              "status": "unaffected",
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              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "4.7",
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                {
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive().\n\nudp_tunnel_sock_release() could set sk-\u003esk_user_data to NULL\nwhile vxlan_gro_prepare_receive() is running.\n\nLet\u0027s check if rcu_dereference_sk_user_data() is NULL after\nskb_gro_remcsum_init()."
        }
      ],
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            "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 - The bug is in vxlan_gro_prepare_receive() on the UDP GRO receive path; remote VXLAN/UDP packets reach it via inet_gro_receive\u2192udp4_gro_receive\u2192udp_tunnel_gro_rcv\u2192vxlan_gro_receive during NAPI processing on internet/cloud overlay endpoints.\nAC:L - An attacker can reliably trigger the race by flooding VXLAN GRO packets while concurrently tearing down the VXLAN device (e.g., via CAP_NET_ADMIN in a user namespace); repeated attempts during orchestrated interface churn also make the timing window attacker-driven rather than purely environmental.\nPR:N - Exploitation requires only the ability to send crafted VXLAN UDP traffic to a listening tunnel port; no target credentials or local account are needed, and concurrent teardown can occur from normal administrative or automation activity rather than attacker-held privileges.\nUI:N - No victim interaction is required beyond the host already running a VXLAN interface; the attacker triggers the fault purely by sending network packets timed against interface teardown.\nS:U - Impact is a kernel fault in networking softirq context on the same host; it does not cross VM, container, or IOMMU security boundaries into another authority.\nC:H - The race can leave a stale vxlan_sock pointer after udp_tunnel_sock_release() frees sk_user_data; dereferencing vs-\u003eflags is a use-after-free read that can expose kernel heap contents and is treated as arbitrary read potential under conservative scoring.\nI:H - Use-after-free on the vxlan_sock object during GRO teardown can corrupt heap metadata or adjacent objects and be leveraged for control-flow hijacking, not merely a benign NULL check failure.\nA:H - A successful trigger causes a kernel NULL pointer dereference/oops in NAPI/softirq context (documented crash at vxlan_gro_prepare_receive), typically crashing or hanging the host and denying all services."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:46:49.365Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/30a45c0bffdd62350261e2f2689fdba426a33578"
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      ],
      "title": "vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive().",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74406",
    "datePublished": "2026-08-15T05:59:15.385Z",
    "dateReserved": "2026-08-15T05:44:03.892Z",
    "dateUpdated": "2026-08-17T05:46:49.365Z",
    "state": "PUBLISHED"
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  "dataType": "CVE_RECORD",
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}

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.

Detection rules are retrieved from Rulezet.

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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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