CVE-2026-90138 (GCVE-0-2026-90138)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:06 – Updated: 2026-09-17 16:06
VLAI
Title
vsock: don't check the listener's sk_err in vsock_accept()
Summary
In the Linux kernel, the following vulnerability has been resolved: vsock: don't check the listener's sk_err in vsock_accept() Syzbot reported an issue which can be reproduced with these steps: r0 = socket(AF_VSOCK, SOCK_STREAM, 0) bind(r0, {VMADDR_CID_ANY, PORT}) connect(r0, {VMADDR_CID_LOCAL, PORT}) -> -1, EPROTO (self-connect) listen(r0, backlog) -> 0 r1 = socket(AF_VSOCK, SOCK_STREAM, 0) connect(r1, {VMADDR_CID_LOCAL, PORT}) -> 0 accept(r0) -> -1, EPROTO (stale sk_err) Basically, it creates a socket (r0) and triggers a self-connect after binding it. This self-connect fails with EPROTO because it loops back to r0 while the socket is still in the TCP_SYN_SENT state, causing it to be incorrectly dispatched to the connecting-client path. The unexpected packet type encountered there sets sk_err to EPROTO. After that, it invokes a listen() call on the same socket. This listen() call succeeds because the kernel's listening path never inspects or clears sk_err. Then, a new socket (r1) is created as a normal client and connects to r0. However, vsock_accept() rejects this incoming connection because the listener's sk_err still holds the EPROTO error from the earlier failed self-connect. This rejection causes the child socket created for r1's connection to never be freed on virtio or hyperv transports; only the VMCI transport implements pending_work to revisit and clean up a rejected socket. For a non-blocking connect(), vsock_connect() may return -EINPROGRESS immediately, and vsock_connect_timeout() can later set sk->sk_err asynchronously. Since no vsock transport ever sets sk_err on a socket while it is in TCP_LISTEN state, checking it in vsock_accept() serves no purpose and only carries forward errors left behind by earlier, unrelated connection attempts on the same socket. Remove the checks so accept() no longer rejects valid incoming connections because of a stale error, which also avoids the resource leak described above.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: d021c344051af91f42c5ba9fdedc176740cbd238 , < c5a75d37c21e558cc6fad1597e732ead30745eed (git)
Affected: d021c344051af91f42c5ba9fdedc176740cbd238 , < 36e5fa009f98a4edbe1783ac11c0df672b224742 (git)
Affected: d021c344051af91f42c5ba9fdedc176740cbd238 , < 491b368a0c6e5f28b615a50b0d384f5c25fde2a7 (git)
Affected: d021c344051af91f42c5ba9fdedc176740cbd238 , < b8c899cf5e7be29840a172c183dedd8d3e7a0287 (git)
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Linux Linux Affected: 3.9
Unaffected: 0 , < 3.9 (semver)
Unaffected: 6.12.110 , ≤ 6.12.* (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "net/vmw_vsock/af_vsock.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvsock: don\u0027t check the listener\u0027s sk_err in vsock_accept()\n\nSyzbot reported an issue which can be reproduced with these steps:\n\tr0 = socket(AF_VSOCK, SOCK_STREAM, 0)\n\tbind(r0, {VMADDR_CID_ANY, PORT})\n\tconnect(r0, {VMADDR_CID_LOCAL, PORT}) -\u003e -1, EPROTO (self-connect)\n\tlisten(r0, backlog)                   -\u003e 0\n\tr1 = socket(AF_VSOCK, SOCK_STREAM, 0)\n\tconnect(r1, {VMADDR_CID_LOCAL, PORT}) -\u003e 0\n\taccept(r0)                            -\u003e -1, EPROTO (stale sk_err)\n\nBasically, it creates a socket (r0) and triggers a self-connect after\nbinding it. This self-connect fails with EPROTO because it loops back\nto r0 while the socket is still in the TCP_SYN_SENT state, causing it\nto be incorrectly dispatched to the connecting-client path. The\nunexpected packet type encountered there sets sk_err to EPROTO.\n\nAfter that, it invokes a listen() call on the same socket. This\nlisten() call succeeds because the kernel\u0027s listening path never\ninspects or clears sk_err. Then, a new socket (r1) is created as a\nnormal client and connects to r0. However, vsock_accept() rejects this\nincoming connection because the listener\u0027s sk_err still holds the\nEPROTO error from the earlier failed self-connect.\n\nThis rejection causes the child socket created for r1\u0027s connection to\nnever be freed on virtio or hyperv transports; only the VMCI transport\nimplements pending_work to revisit and clean up a rejected socket.\n\nFor a non-blocking connect(), vsock_connect() may return -EINPROGRESS\nimmediately, and vsock_connect_timeout() can later set sk-\u003esk_err\nasynchronously.\n\nSince no vsock transport ever sets sk_err on a socket while it is in\nTCP_LISTEN state, checking it in vsock_accept() serves no purpose and\nonly carries forward errors left behind by earlier, unrelated\nconnection attempts on the same socket. Remove the checks so accept()\nno longer rejects valid incoming connections because of a stale\nerror, which also avoids the resource leak described above."
        }
      ],
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        "dateUpdated": "2026-09-17T16:06:36.528Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/b8c899cf5e7be29840a172c183dedd8d3e7a0287"
        }
      ],
      "title": "vsock: don\u0027t check the listener\u0027s sk_err in vsock_accept()",
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    "cveId": "CVE-2026-90138",
    "datePublished": "2026-09-17T16:06:36.528Z",
    "dateReserved": "2026-09-11T19:38:34.788Z",
    "dateUpdated": "2026-09-17T16:06:36.528Z",
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        "descriptions": [
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            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvsock: don\u0027t check the listener\u0027s sk_err in vsock_accept()\n\nSyzbot reported an issue which can be reproduced with these steps:\n\tr0 = socket(AF_VSOCK, SOCK_STREAM, 0)\n\tbind(r0, {VMADDR_CID_ANY, PORT})\n\tconnect(r0, {VMADDR_CID_LOCAL, PORT}) -\u003e -1, EPROTO (self-connect)\n\tlisten(r0, backlog)                   -\u003e 0\n\tr1 = socket(AF_VSOCK, SOCK_STREAM, 0)\n\tconnect(r1, {VMADDR_CID_LOCAL, PORT}) -\u003e 0\n\taccept(r0)                            -\u003e -1, EPROTO (stale sk_err)\n\nBasically, it creates a socket (r0) and triggers a self-connect after\nbinding it. This self-connect fails with EPROTO because it loops back\nto r0 while the socket is still in the TCP_SYN_SENT state, causing it\nto be incorrectly dispatched to the connecting-client path. The\nunexpected packet type encountered there sets sk_err to EPROTO.\n\nAfter that, it invokes a listen() call on the same socket. This\nlisten() call succeeds because the kernel\u0027s listening path never\ninspects or clears sk_err. Then, a new socket (r1) is created as a\nnormal client and connects to r0. However, vsock_accept() rejects this\nincoming connection because the listener\u0027s sk_err still holds the\nEPROTO error from the earlier failed self-connect.\n\nThis rejection causes the child socket created for r1\u0027s connection to\nnever be freed on virtio or hyperv transports; only the VMCI transport\nimplements pending_work to revisit and clean up a rejected socket.\n\nFor a non-blocking connect(), vsock_connect() may return -EINPROGRESS\nimmediately, and vsock_connect_timeout() can later set sk-\u003esk_err\nasynchronously.\n\nSince no vsock transport ever sets sk_err on a socket while it is in\nTCP_LISTEN state, checking it in vsock_accept() serves no purpose and\nonly carries forward errors left behind by earlier, unrelated\nconnection attempts on the same socket. Remove the checks so accept()\nno longer rejects valid incoming connections because of a stale\nerror, which also avoids the resource leak described above."
          }
        ],
        "id": "CVE-2026-90138",
        "lastModified": "2026-09-17T17:17:06.407",
        "metrics": {},
        "published": "2026-09-17T17:17:06.407",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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