GHSA-9PRJ-6XM5-HXJF

Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-17 18:32
VLAI
Details

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

bpf: Fix potential UAF in bpf_netns_link_update_prog

In bpf_netns_link_update_prog, the checks for old_prog and prog type are currently performed locklessly before acquiring netns_bpf_mutex. This creates a race condition that can lead to a UAF issue.

If two threads concurrently execute BPF_LINK_UPDATE on the same netns link, the following execution path can trigger a UAF:

CPU0 CPU1 bpf_netns_link_update_prog if (old_prog && old_prog != link->prog) return -EPERM; bpf_netns_link_update_prog if (old_prog && old_prog != link->prog) ... old_prog = xchg(&link->prog, new_prog); bpf_prog_put(old_prog); if (new_prog->type != link->prog->type) <-- trigger UAF

Fix this by moving the old_prog and prog->type checks inside the netns_bpf_mutex critical section. Meanwhile, use guard() to simplify lock management and avoid all the goto jumping.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-90393"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-17T17:17:38Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix potential UAF in bpf_netns_link_update_prog\n\nIn bpf_netns_link_update_prog, the checks for old_prog and prog type\nare currently performed locklessly before acquiring netns_bpf_mutex.\nThis creates a race condition that can lead to a UAF issue.\n\nIf two threads concurrently execute BPF_LINK_UPDATE on the same netns\nlink, the following execution path can trigger a UAF:\n\nCPU0                                          CPU1\nbpf_netns_link_update_prog\n  if (old_prog \u0026\u0026 old_prog != link-\u003eprog)\n    return -EPERM;\n                                              bpf_netns_link_update_prog\n                                                if (old_prog \u0026\u0026 old_prog != link-\u003eprog)\n                                                ...\n                                                old_prog = xchg(\u0026link-\u003eprog, new_prog);\n                                                bpf_prog_put(old_prog);\n  if (new_prog-\u003etype != link-\u003eprog-\u003etype) \u003c-- trigger UAF\n\nFix this by moving the old_prog and prog-\u003etype checks inside the\nnetns_bpf_mutex critical section. Meanwhile, use guard() to simplify\nlock management and avoid all the goto jumping.",
  "id": "GHSA-9prj-6xm5-hxjf",
  "modified": "2026-09-17T18:32:04Z",
  "published": "2026-09-17T18:32:03Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90393"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/277168cb9d153ce8e9c3f9275670e32ae61b41d6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5c5997836381010fc5907b36bc17d3b19407e933"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/79a66fd997d4eecf17302d613194879eb32e0986"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/923f559e95b89b33c7e1793b3d8f7f4ec9b2e4b7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bda86e9f31b9a296b6e64a51c91dc776fc9f613e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bdddf3e1493ee973619c154a57071ce67f78598b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d462b5481d77ce7df8a5ff89a699386f00c9214d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f4ce6803df4095777191d800bebc50219b615ca0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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