Vulnerability-Lookup

GHSA-6X4X-6P4P-6F5F

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:

netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types

Sashiko pointed out that there are a few lockless RCU readers using test_bit() which is a relaxed atomic operation and provides no memory barrier guarantees. Use test_bit_acquire() instead where the operation may run parallel with add/del/gc, i.e. is not one from the next cases

protected by region lock
in a set destroy phase
in a new/temporary set creation phase

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-2026-72436"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:17Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ipset: Don\u0027t use test_bit() in lockless RCU readers in hash types\n\nSashiko pointed out that there are a few lockless RCU readers\nusing test_bit() which is a relaxed atomic operation and\nprovides no memory barrier guarantees. Use test_bit_acquire()\ninstead where the operation may run parallel with add/del/gc,\ni.e. is not one from the next cases\n\n- protected by region lock\n- in a set destroy phase\n- in a new/temporary set creation phase",
  "id": "GHSA-6x4x-6p4p-6f5f",
  "modified": "2026-08-17T06:33:29Z",
  "published": "2026-08-15T06:32:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72436"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3219d74e4536658c937fd878a327257b86ce80dd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6329d3a9afe715fddda0460cfa46b496d61c2fe0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7445fe965b7d8756070a40e80f8b73348ccda1d7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c107233d2ff4fd7cef5d02f9124b99194957a710"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c4d257734e91bfcdc71d41843392dd6400b5bb1b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e4b4984e28c16406ecb318444dea4a8bf47def3e"
    }
  ],
  "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-2026-72436 (GCVE-0-2026-72436)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:44

Title

netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types Sashiko pointed out that there are a few lockless RCU readers using test_bit() which is a relaxed atomic operation and provides no memory barrier guarantees. Use test_bit_acquire() instead where the operation may run parallel with add/del/gc, i.e. is not one from the next cases - protected by region lock - in a set destroy phase - in a new/temporary set creation phase

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/c107233d2ff4fd7ce…
https://git.kernel.org/stable/c/6329d3a9afe715fdd…
https://git.kernel.org/stable/c/7445fe965b7d87560…
https://git.kernel.org/stable/c/c4d257734e91bfcdc…
https://git.kernel.org/stable/c/3219d74e4536658c9…
https://git.kernel.org/stable/c/e4b4984e28c16406e…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 18f84d41d34fa35d0d64bbaea01fe664553ecc06 , < c107233d2ff4fd7cef5d02f9124b99194957a710 (git) Affected: 18f84d41d34fa35d0d64bbaea01fe664553ecc06 , < 6329d3a9afe715fddda0460cfa46b496d61c2fe0 (git) Affected: 18f84d41d34fa35d0d64bbaea01fe664553ecc06 , < 7445fe965b7d8756070a40e80f8b73348ccda1d7 (git) Affected: 18f84d41d34fa35d0d64bbaea01fe664553ecc06 , < c4d257734e91bfcdc71d41843392dd6400b5bb1b (git) Affected: 18f84d41d34fa35d0d64bbaea01fe664553ecc06 , < 3219d74e4536658c937fd878a327257b86ce80dd (git) Affected: 18f84d41d34fa35d0d64bbaea01fe664553ecc06 , < e4b4984e28c16406ecb318444dea4a8bf47def3e (git)
Linux	Linux	Affected: 4.2 Unaffected: 0 , < 4.2 (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": [
            "net/netfilter/ipset/ip_set_hash_gen.h"
          ],
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          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c107233d2ff4fd7cef5d02f9124b99194957a710",
              "status": "affected",
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              "versionType": "git"
            },
            {
              "lessThan": "6329d3a9afe715fddda0460cfa46b496d61c2fe0",
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              "versionType": "git"
            },
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              "versionType": "git"
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            {
              "lessThan": "3219d74e4536658c937fd878a327257b86ce80dd",
              "status": "affected",
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              "version": "18f84d41d34fa35d0d64bbaea01fe664553ecc06",
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
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          "vendor": "Linux",
          "versions": [
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            {
              "lessThan": "4.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
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            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.178",
                  "versionStartIncluding": "4.2",
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                  "versionStartIncluding": "4.2",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ipset: Don\u0027t use test_bit() in lockless RCU readers in hash types\n\nSashiko pointed out that there are a few lockless RCU readers\nusing test_bit() which is a relaxed atomic operation and\nprovides no memory barrier guarantees. Use test_bit_acquire()\ninstead where the operation may run parallel with add/del/gc,\ni.e. is not one from the next cases\n\n- protected by region lock\n- in a set destroy phase\n- in a new/temporary set creation phase"
        }
      ],
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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 vulnerable mtype_test() runs on every packet matched by iptables/nftables xt_set rules in PREROUTING/INPUT/FORWARD, so a remote attacker reaches the bug by sending network traffic to internet-facing servers using ipset-based firewall blocklists.\nAC:L - The attacker controls both sides of the race by flooding packets that trigger lockless RCU readers while concurrently driving hash add/del via SET target rules or timeout GC on the same ipset, making the memory-ordering race reliably winnable.\nPR:N - No credentials or local access are required on the target; exploitation needs only unauthenticated network packets to a host running ipset netfilter rules, a standard deployment on firewalls, mail servers, and CDN edge nodes.\nUI:N - No victim interaction is needed; the attack is fully automated by sending network traffic and does not require mounting filesystems, opening files, or any other user action.\nS:U - The vulnerability corrupts or leaks kernel heap data within the same host security boundary; it does not cross VM, container, or IOMMU isolation boundaries.\nC:H - Without acquire semantics, test_bit() can observe a slot as used before element writes are visible or after deletion, causing reads of uninitialized, stale, or freed hbucket element and extension memory\u2014a UAF-class kernel information disclosure.\nI:H - Stale or torn reads of hash bucket elements during concurrent add/del/gc constitute kernel heap memory safety violations that can corrupt netfilter matching decisions and be further leveraged for control-flow or data manipulation attacks.\nA:H - Reading partially initialized or post-destroy hash element memory during softirq packet processing on loaded firewall datapaths can trigger kernel oopses, panics, or hangs, causing complete loss of availability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:44:12.018Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/e4b4984e28c16406ecb318444dea4a8bf47def3e"
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      ],
      "title": "netfilter: ipset: Don\u0027t use test_bit() in lockless RCU readers in hash types",
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    "cveId": "CVE-2026-72436",
    "datePublished": "2026-08-15T05:56:50.051Z",
    "dateReserved": "2026-08-09T03:40:39.929Z",
    "dateUpdated": "2026-08-17T05:44:12.018Z",
    "state": "PUBLISHED"
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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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