Vulnerability-Lookup

GHSA-6PXH-C54R-CXC3

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:

bpf: Fix effective prog array index with BPF_F_PREORDER

replace_effective_prog() and purge_effective_progs() located the slot in the effective array by walking the program hlist and counting entries linearly. That count does not match the array layout: compute_effective_ progs() places BPF_F_PREORDER programs at the front (ancestor cgroup first, attach order within a cgroup) and the rest after them (descendant cgroup first). So when a preorder program is present, the linear hlist position no longer equals the program's index in the effective array.

For replace_effective_prog() (bpf_link_update()) this overwrote the wrong slot, corrupting the effective order. For purge_effective_progs(), it could dummy out a slot belonging to a different program and leave the detached program in the array while bpf_prog_put() drops its reference, i.e. a use-after-free.

Fix both by replaying compute_effective_progs()'s placement (including the per-cgroup preorder reversal) in a shared effective_prog_pos() helper. Identify the entry by its struct bpf_prog_list pointer rather than by (prog, link) value, so the lookup resolves to exactly the attachment the syscall selected even when the same bpf_prog is attached to several cgroups in the hierarchy.

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-2026-72427"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:22:16Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix effective prog array index with BPF_F_PREORDER\n\nreplace_effective_prog() and purge_effective_progs() located the slot in\nthe effective array by walking the program hlist and counting entries\nlinearly. That count does not match the array layout: compute_effective_\nprogs() places BPF_F_PREORDER programs at the front (ancestor cgroup\nfirst, attach order within a cgroup) and the rest after them (descendant\ncgroup first). So when a preorder program is present, the linear hlist\nposition no longer equals the program\u0027s index in the effective array.\n\nFor replace_effective_prog() (bpf_link_update()) this overwrote the\nwrong slot, corrupting the effective order. For purge_effective_progs(),\nit could dummy out a slot belonging to a different program and leave the\ndetached program in the array while bpf_prog_put() drops its reference,\ni.e. a use-after-free.\n\nFix both by replaying compute_effective_progs()\u0027s placement (including\nthe per-cgroup preorder reversal) in a shared effective_prog_pos()\nhelper. Identify the entry by its struct bpf_prog_list pointer rather\nthan by (prog, link) value, so the lookup resolves to exactly the\nattachment the syscall selected even when the same bpf_prog is attached\nto several cgroups in the hierarchy.",
  "id": "GHSA-6pxh-c54r-cxc3",
  "modified": "2026-08-17T06:33:29Z",
  "published": "2026-08-15T06:32:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72427"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/41b4320b84fdafe1ab586b06453d30d50415db59"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/525e408c27ae714e538b8c608c3a974df3ab6c92"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9697db03e010391c55ae75192cbdf30c5a72c114"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b584f107ab90222bd825dcb4c5977326ff684109"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f08aaee3152d0dfc578b3f2586932d82062701dd"
    }
  ],
  "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-2026-72427 (GCVE-0-2026-72427)

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

Title

bpf: Fix effective prog array index with BPF_F_PREORDER

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix effective prog array index with BPF_F_PREORDER replace_effective_prog() and purge_effective_progs() located the slot in the effective array by walking the program hlist and counting entries linearly. That count does not match the array layout: compute_effective_ progs() places BPF_F_PREORDER programs at the front (ancestor cgroup first, attach order within a cgroup) and the rest after them (descendant cgroup first). So when a preorder program is present, the linear hlist position no longer equals the program's index in the effective array. For replace_effective_prog() (bpf_link_update()) this overwrote the wrong slot, corrupting the effective order. For purge_effective_progs(), it could dummy out a slot belonging to a different program and leave the detached program in the array while bpf_prog_put() drops its reference, i.e. a use-after-free. Fix both by replaying compute_effective_progs()'s placement (including the per-cgroup preorder reversal) in a shared effective_prog_pos() helper. Identify the entry by its struct bpf_prog_list pointer rather than by (prog, link) value, so the lookup resolves to exactly the attachment the syscall selected even when the same bpf_prog is attached to several cgroups in the hierarchy.

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

5 references

URL	Tags
https://git.kernel.org/stable/c/525e408c27ae714e5…
https://git.kernel.org/stable/c/41b4320b84fdafe1a…
https://git.kernel.org/stable/c/9697db03e010391c5…
https://git.kernel.org/stable/c/b584f107ab90222bd…
https://git.kernel.org/stable/c/f08aaee3152d0dfc5…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: bc8023ef3b11410682e5d4990e05e5bc2d3e1c94 , < 525e408c27ae714e538b8c608c3a974df3ab6c92 (git) Affected: 555c0b713ca83968d3c843cb15485b9ba3367b1b , < 41b4320b84fdafe1ab586b06453d30d50415db59 (git) Affected: 4b82b181a26cff8bf7adc3a85a88d121d92edeaf , < 9697db03e010391c55ae75192cbdf30c5a72c114 (git) Affected: 4b82b181a26cff8bf7adc3a85a88d121d92edeaf , < b584f107ab90222bd825dcb4c5977326ff684109 (git) Affected: 4b82b181a26cff8bf7adc3a85a88d121d92edeaf , < f08aaee3152d0dfc578b3f2586932d82062701dd (git) Affected: 4707ad649cf662add3058bff47430817811b048d (git) Affected: 6.6.93 , < 6.6.145 (semver) Affected: 6.12.31 , < 6.12.97 (semver) Affected: 6.14.9 , < 6.15 (semver)
Linux	Linux	Affected: 6.15 Unaffected: 0 , < 6.15 (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": [
            "kernel/bpf/cgroup.c"
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              "lessThan": "525e408c27ae714e538b8c608c3a974df3ab6c92",
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              "versionType": "semver"
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              "status": "unaffected",
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              "value": "AV:L - Exploitation requires local bpf() syscalls (BPF_LINK_CREATE/BPF_PROG_ATTACH with BPF_F_PREORDER, BPF_LINK_UPDATE, BPF_PROG_DETACH/BPF_LINK_DETACH) through __cgroup_bpf_replace/__cgroup_bpf_detach in kernel/bpf/cgroup.c; per kernel CNA guidance BPF cgroup hooks are Local even when later triggered by packets.\nAC:L - Attacker fully controls cgroup hierarchy, BPF_F_PREORDER|BPF_F_ALLOW_MULTI attachments, and bpf_link_update/detach timing; purge_effective_progs UAF needs update_effective_progs() OOM which attacker can induce via memory pressure/large hierarchies, and bpf_link_update ordering corruption triggers without OOM.\nPR:L - Reaching the bug requires CAP_BPF (and CAP_NET_ADMIN for most cgroup BPF types) plus cgroup v2 attach access, commonly obtainable by unprivileged users via delegated cgroups or user namespaces (CAP_BPF/CAP_NET_ADMIN), not init-namespace root.\nUI:N - Attacker loads, attaches, and updates/detaches their own cgroup BPF programs and links via bpf(); no separate victim or administrator action is required.\nS:U - The bug corrupts kernel cgroup BPF effective-prog arrays causing UAF/ordering corruption within the same kernel security domain, enabling local privilege escalation rather than crossing VM, IOMMU, or sandbox boundaries.\nC:H - purge_effective_progs() can leave a detached bpf_prog pointer in the RCU-protected effective array while bpf_prog_put() frees it, yielding a use-after-free read when __cgroup_bpf_run_filter_* later executes the stale program under RCU.\nI:H - UAF of bpf_prog objects enables heap reuse for arbitrary kernel writes/control-flow hijack; bpf_link_update() mis-indexing can overwrite another attachment\u0027s effective slot so attacker-controlled BPF runs in place of security/filter programs on traffic for the whole cgroup tree.\nA:H - Freed-but-still-referenced programs are executed from softirq/network cgroup hooks and reliably cause kernel oops/panic/KASAN failures; ordering corruption can also crash or hang filtering paths serving container/cloud workloads."
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          "url": "https://git.kernel.org/stable/c/9697db03e010391c55ae75192cbdf30c5a72c114"
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        },
        {
          "url": "https://git.kernel.org/stable/c/f08aaee3152d0dfc578b3f2586932d82062701dd"
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      "title": "bpf: Fix effective prog array index with BPF_F_PREORDER",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72427",
    "datePublished": "2026-08-15T05:56:44.197Z",
    "dateReserved": "2026-08-09T03:40:39.928Z",
    "dateUpdated": "2026-08-17T05:44:07.623Z",
    "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.

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GHSA-6PXH-C54R-CXC3

CVE-2026-72427 (GCVE-0-2026-72427)

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Sightings

Nomenclature