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GHSA-WGC9-J6GH-934M

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:

dlm: fix add msg handle in send_queue ordered

In a benchmark scenario triggering a lot of requests that triggers a lot of DLM messages on the network it can be that the mh->seq is not ordered according the oldest seq number. This ordering is required by dlm_receive_ack as "before(mh->seq, seq)" will stop to check for older sequence numbers that are ordered in the tail of "node->send_queue".

The side effects of not having it correct ordered regarding "before(mh->seq, seq)" are refcounting issues and use-after free.

I only was able to reproduce this issue in a experimental DLM branch and a user space DLM benchmark that uses io_uring. After changing this I don't experienced any refcounting with the sending buffer issues anymore.

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-2026-74401"
  ],
  "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\ndlm: fix add msg handle in send_queue ordered\n\nIn a benchmark scenario triggering a lot of requests that triggers a lot\nof DLM messages on the network it can be that the mh-\u003eseq is not ordered\naccording the oldest seq number. This ordering is required by\ndlm_receive_ack as \"before(mh-\u003eseq, seq)\" will stop to check for older\nsequence numbers that are ordered in the tail of \"node-\u003esend_queue\".\n\nThe side effects of not having it correct ordered regarding\n\"before(mh-\u003eseq, seq)\" are refcounting issues and use-after free.\n\nI only was able to reproduce this issue in a experimental DLM branch\nand a user space DLM benchmark that uses io_uring. After changing this I\ndon\u0027t experienced any refcounting with the sending buffer issues anymore.",
  "id": "GHSA-wgc9-j6gh-934m",
  "modified": "2026-08-17T06:33:43Z",
  "published": "2026-08-15T06:32:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-74401"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4d45250b1d22960f86d83245be188b16e456218b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6369619f1b665f12d8c99cc6ff733c64eb08b22e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/712714f818d83373847874ab0f8e426be79296cf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ae9e534e502a0f48c12baf83608c5de0ff0eab11"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d2248cb70c070f8f04762872772e155b59016f17"
    }
  ],
  "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-2026-74401 (GCVE-0-2026-74401)

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

Title

dlm: fix add msg handle in send_queue ordered

Summary

In the Linux kernel, the following vulnerability has been resolved: dlm: fix add msg handle in send_queue ordered In a benchmark scenario triggering a lot of requests that triggers a lot of DLM messages on the network it can be that the mh->seq is not ordered according the oldest seq number. This ordering is required by dlm_receive_ack as "before(mh->seq, seq)" will stop to check for older sequence numbers that are ordered in the tail of "node->send_queue". The side effects of not having it correct ordered regarding "before(mh->seq, seq)" are refcounting issues and use-after free. I only was able to reproduce this issue in a experimental DLM branch and a user space DLM benchmark that uses io_uring. After changing this I don't experienced any refcounting with the sending buffer issues anymore.

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

5 references

URL	Tags
https://git.kernel.org/stable/c/ae9e534e502a0f48c…
https://git.kernel.org/stable/c/6369619f1b665f12d…
https://git.kernel.org/stable/c/712714f818d833738…
https://git.kernel.org/stable/c/4d45250b1d22960f8…
https://git.kernel.org/stable/c/d2248cb70c070f8f0…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 489d8e559c6596eb08e16447d9830bc39afbe54e , < ae9e534e502a0f48c12baf83608c5de0ff0eab11 (git) Affected: 489d8e559c6596eb08e16447d9830bc39afbe54e , < 6369619f1b665f12d8c99cc6ff733c64eb08b22e (git) Affected: 489d8e559c6596eb08e16447d9830bc39afbe54e , < 712714f818d83373847874ab0f8e426be79296cf (git) Affected: 489d8e559c6596eb08e16447d9830bc39afbe54e , < 4d45250b1d22960f86d83245be188b16e456218b (git) Affected: 489d8e559c6596eb08e16447d9830bc39afbe54e , < d2248cb70c070f8f04762872772e155b59016f17 (git)
Linux	Linux	Affected: 5.14 Unaffected: 0 , < 5.14 (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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JSON

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      "affected": [
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          "defaultStatus": "unaffected",
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              "value": "AV:N - The UAF is triggered in dlm_receive_ack when processing DLM_ACK packets from remote cluster peers over lowcomms TCP/SCTP port 21064 (receive_from_sock -\u003e dlm_process_incoming_buffer -\u003e dlm_midcomms_receive_buffer_3_2); wire ACK sequence numbers directly drive premature dlm_mhandle_delete on the victim.\nAC:L - The send_queue ordering race in midcomms_new_msg_cb is hit under heavy concurrent DLM traffic; an attacker controls both sides by flooding lock requests from a cluster peer (io_uring benchmark per fix author) while sending ACKs, without depending on timing they cannot influence.\nPR:N - DLM has no authentication or TLS; the only gate is source IP matching a configured cluster node in addr_to_nodeid. A compromised cluster peer or attacker on the cluster network needs no Unix account or local privileges on the victim to deliver crafted DLM_ACK packets.\nUI:N - No victim user action is required; ACKs and lock traffic are processed automatically on already-running HA cluster nodes (GFS2/OCFS2/Pacemaker) by DLM receive and send workqueues without any interactive step.\nS:U - Impact is confined to kernel heap and refcount corruption within the victim node\u0027s kernel address space; no VM, IOMMU, or sandbox boundary is crossed\u2014standard kernel UAF enabling privilege escalation on the same host.\nC:H - Misordered send_queue causes dlm_receive_ack to skip or prematurely free mhandles via call_rcu/dlm_mhandle_release while references still exist; UAF reads from freed slab objects enable heap grooming and arbitrary kernel memory disclosure.\nI:H - Premature dlm_mhandle_delete releases in-flight mh-\u003emsg buffers and corrupts kref counts while commit paths still dereference the handle; UAF write primitives via reclaimed slab data can hijack kernel control flow per DLM UAF scoring guidance.\nA:H - Refcounting corruption and use-after-free in dlm_receive_ack reliably cause KASAN splats, kernel oopses, and cluster-wide availability loss when DLM on HA nodes handling GFS2/OCFS2 lock traffic crashes or hangs."
            }
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        "dateUpdated": "2026-08-17T05:46:44.230Z",
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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.

Related by attack behaviour

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