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GHSA-W888-J23Q-C78G

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:

net: udp_tunnel: prevent double queueing in udp_tunnel_nic_device_sync

Yue Sun reported a use-after-free and debugobjects warning in udp_tunnel_nic_device_sync_work() during concurrent device operations.

The workqueue core clears the internal pending bit before invoking the worker. At that point, a concurrent thread can queue the work again. When the already running worker eventually clears the work_pending flag to 0, it mistakenly clears the flag for the newly queued instance. udp_tunnel_nic_unregister() then observes work_pending as 0 and frees the structure while the second work item is still active in the queue, leading to UAF.

Fix this by returning early in udp_tunnel_nic_device_sync() if work_pending is already set, preventing redundant work queueing.

Severity

7.8 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-72405"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:14Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: udp_tunnel: prevent double queueing in udp_tunnel_nic_device_sync\n\nYue Sun reported a use-after-free and debugobjects warning in\nudp_tunnel_nic_device_sync_work() during concurrent device operations.\n\nThe workqueue core clears the internal pending bit before invoking the\nworker. At that point, a concurrent thread can queue the work again.\nWhen the already running worker eventually clears the work_pending flag\nto 0, it mistakenly clears the flag for the newly queued instance.\nudp_tunnel_nic_unregister() then observes work_pending as 0 and frees\nthe structure while the second work item is still active in the queue,\nleading to UAF.\n\nFix this by returning early in udp_tunnel_nic_device_sync() if\nwork_pending is already set, preventing redundant work queueing.",
  "id": "GHSA-w888-j23q-c78g",
  "modified": "2026-08-17T06:33:28Z",
  "published": "2026-08-15T06:32:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72405"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/54292b167466cdf42176b7b6f01da66c184deb12"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9075efb9b2c1d9d7a8285c937b64aa93ca0c41b7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cee6688e5731c0591643521716d1a1a5c1a98bf8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ecf69d4b43370c587e48d4d70289dbdb7e039d4d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-72405 (GCVE-0-2026-72405)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43

Title

net: udp_tunnel: prevent double queueing in udp_tunnel_nic_device_sync

Summary

In the Linux kernel, the following vulnerability has been resolved: net: udp_tunnel: prevent double queueing in udp_tunnel_nic_device_sync Yue Sun reported a use-after-free and debugobjects warning in udp_tunnel_nic_device_sync_work() during concurrent device operations. The workqueue core clears the internal pending bit before invoking the worker. At that point, a concurrent thread can queue the work again. When the already running worker eventually clears the work_pending flag to 0, it mistakenly clears the flag for the newly queued instance. udp_tunnel_nic_unregister() then observes work_pending as 0 and frees the structure while the second work item is still active in the queue, leading to UAF. Fix this by returning early in udp_tunnel_nic_device_sync() if work_pending is already set, preventing redundant work queueing.

Severity

7.8 (High)


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

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/cee6688e5731c0591…
https://git.kernel.org/stable/c/9075efb9b2c1d9d7a…
https://git.kernel.org/stable/c/54292b167466cdf42…
https://git.kernel.org/stable/c/ecf69d4b43370c587…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: cc4e3835eff474aa274d6e1d18f69d9d296d3b76 , < cee6688e5731c0591643521716d1a1a5c1a98bf8 (git) Affected: cc4e3835eff474aa274d6e1d18f69d9d296d3b76 , < 9075efb9b2c1d9d7a8285c937b64aa93ca0c41b7 (git) Affected: cc4e3835eff474aa274d6e1d18f69d9d296d3b76 , < 54292b167466cdf42176b7b6f01da66c184deb12 (git) Affected: cc4e3835eff474aa274d6e1d18f69d9d296d3b76 , < ecf69d4b43370c587e48d4d70289dbdb7e039d4d (git)
Linux	Linux	Affected: 5.9 Unaffected: 0 , < 5.9 (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": [
            "net/ipv4/udp_tunnel_nic.c"
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              "versionType": "git"
            },
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              "status": "affected",
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          "versions": [
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              "versionType": "semver"
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              "versionType": "semver"
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              "versionType": "semver"
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        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.97",
                  "versionStartIncluding": "5.9",
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        }
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          },
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              "value": "AV:L - The bug is reached only through local netlink/RTNL paths (VXLAN/Geneve tunnel socket create/delete, netdev feature updates, or netdev unregister) that queue udp_tunnel_nic_device_sync; remote UDP/VXLAN packets do not enter this offload management code.\nAC:L - An attacker can reliably win the race by running concurrent tunnel create/delete or netdev operations in multiple threads; both the double-queue and the premature free depend on attacker-controlled timing, not on uncontrollable system state.\nPR:L - Triggering udp_tunnel_notify_add/del_rx_port requires CAP_NET_ADMIN (e.g. ip link add/del vxlan/geneve), which unprivileged users can obtain in a user/network namespace via unshare; no remote or pre-auth network path exists.\nUI:N - Exploitation requires only programmatic tunnel or netdev manipulation via netlink; no victim user action such as opening a file or mounting a filesystem is needed.\nS:U - Impact is kernel heap corruption and potential privilege escalation within the same kernel/host security domain; it does not by itself cross a VM, container, or IOMMU boundary to another authority.\nC:H - The flaw is a use-after-free of struct udp_tunnel_nic; freed offload state can be reallocated and read through the still-queued work handler, enabling arbitrary kernel memory disclosure.\nI:H - UAF on the udp_tunnel_nic work item and its entries allows heap grooming and corrupting kernel objects/driver callbacks, supporting arbitrary write and potential kernel code execution.\nA:H - Use-after-free in a workqueue handler on a shared offload path can cause kernel oops/panic or wedged NIC offload during concurrent tunnel churn, producing total loss of availability."
            }
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        }
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      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:43:45.202Z",
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        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/ecf69d4b43370c587e48d4d70289dbdb7e039d4d"
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      ],
      "title": "net: udp_tunnel: prevent double queueing in udp_tunnel_nic_device_sync",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72405",
    "datePublished": "2026-08-15T05:56:29.466Z",
    "dateReserved": "2026-08-09T03:40:39.925Z",
    "dateUpdated": "2026-08-17T05:43:45.202Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "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.

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.

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GHSA-W888-J23Q-C78G

CVE-2026-72405 (GCVE-0-2026-72405)

Tags

Sightings

Nomenclature