CVE-2026-90057 (GCVE-0-2026-90057)
Vulnerability from cvelistv5
Published
2026-09-17 16:05
Modified
2026-10-19 08:57
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: slip: remove slip_hangup() to fix use-after-free in slip_receive_buf() Jaeyoung Chung and Eulgyu Kim reported a slab-use-after-free read in slip_receive_buf() when racing against tty hangup. tty_ldisc_hangup() calls ld->ops->hangup() while holding only a read lock on tty->ldisc_sem (via tty_ldisc_ref()). Because slip_hangup() simply called slip_close(), it ran concurrently with reader functions such as slip_receive_buf(). slip_close() unregisters and frees the net device and its private struct slip, causing concurrent reader threads in slip_receive_buf() to dereference freed memory. Line discipline close() is already guaranteed to be called under the write lock of tty->ldisc_sem during hangup processing (in tty_ldisc_reinit() or tty_ldisc_kill()). Remove slip_hangup() so teardown is serialized cleanly by slip_close().
References
Impacted products
Vendor Product Version
Linux Linux Version: 5342b77c4123ba39f911d92a813295fb3bb21f69
Version: 5342b77c4123ba39f911d92a813295fb3bb21f69
Version: 5342b77c4123ba39f911d92a813295fb3bb21f69
Version: 5342b77c4123ba39f911d92a813295fb3bb21f69
Version: 5342b77c4123ba39f911d92a813295fb3bb21f69
Version: 5342b77c4123ba39f911d92a813295fb3bb21f69
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/slip/slip.c"
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          "product": "Linux",
          "programFiles": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "0",
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              "status": "unaffected",
              "version": "6.18.52",
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            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
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            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
        {
          "nodes": [
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                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nslip: remove slip_hangup() to fix use-after-free in slip_receive_buf()\n\nJaeyoung Chung and Eulgyu Kim reported a slab-use-after-free read\nin slip_receive_buf() when racing against tty hangup.\n\ntty_ldisc_hangup() calls ld-\u003eops-\u003ehangup() while holding only\na read lock on tty-\u003eldisc_sem (via tty_ldisc_ref()).\nBecause slip_hangup() simply called slip_close(), it ran concurrently\nwith reader functions such as slip_receive_buf().\n\nslip_close() unregisters and frees the net device and its private\nstruct slip, causing concurrent reader threads in slip_receive_buf()\nto dereference freed memory.\n\nLine discipline close() is already guaranteed to be called under\nthe write lock of tty-\u003eldisc_sem during hangup processing\n(in tty_ldisc_reinit() or tty_ldisc_kill()).\n\nRemove slip_hangup() so teardown is serialized cleanly by slip_close()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The UAF is reached by racing local TTY syscalls: ioctl(TIOCSETD, N_SLIP) then write() on a PTY master into pty_write\u2192tty_insert_flip_string_and_push_buffer\u2192flush_to_ldisc\u2192tty_port_default_receive_buf\u2192slip_receive_buf, while close() of that master runs pty_close\u2192tty_vhangup\u2192tty_ldisc_hangup\u2192slip_hangup. Hangup is a local TTY lifecycle event, not bytes from a remote SLIP peer.\nAC:L - The attacker owns both PTY fds and can loop write() on the master (driving slip_receive_buf under tty_ldisc_ref()\u0027s read lock) concurrently with close()\u2192pty_close\u2192tty_vhangup\u2192slip_hangup, which tty_ldisc_hangup() also invokes under only a read lock. Because hangup() is not serialized by ldisc_sem\u0027s write side, the attacker creates and retries the race.\nPR:L - Attaching N_SLIP requires slip_open()\u0027s capable(CAP_NET_ADMIN) check, which is ns_capable(\u0026init_user_ns) and is not granted by unshare -Urn. CAP_NET_ADMIN in the initial user namespace is still routinely given to non-root container/network workloads (Docker/K8s --cap-add=NET_ADMIN) without full host root, so privileges required are Low.\nUI:N - The attacker performs every step in its own processes: open(\"/dev/ptmx\"), ioctl(TIOCSETD, N_SLIP), write() to the master, and close() to force pty_close()\u2192tty_vhangup(). No separate victim user or administrator action is required at exploit time.\nS:U - The UAF corrupts the host-kernel net_device allocated in sl_alloc() via alloc_netdev() and its embedded struct slip (netdev_priv). Impact is standard local kernel privilege escalation, not a VM escape or IOMMU/DMA boundary bypass.\nC:H - slip_receive_buf() loads sl from tty-\u003edisc_data without an RCU read-side critical section, then reads sl-\u003emagic and sl-\u003edev after slip_hangup()\u2192slip_close()\u2192unregister_netdev() has freed that net_device (needs_free_netdev). A use-after-free of this object enables an arbitrary kernel read via heap spray.\nI:H - Once past those checks, slip_receive_buf() takes spin_lock_bh(\u0026sl-\u003elock) and slip_unesc() writes sl-\u003erbuff[sl-\u003ercount++] and sl-\u003eflags on the already-freed struct slip, giving a write primitive against a net_device that also carries netdev_ops function pointers.\nA:H - Use-after-free of the SLIP net_device/struct slip causes a kernel oops or panic even when not fully exploited; the report is a KASAN slab-use-after-free read in slip_receive_buf() racing tty hangup."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:57:14.597Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9a3b1edff1ecb47d323f2506b3ffc22178acd1c6"
        },
        {
          "url": "https://git.kernel.org/stable/c/a2dbac3fb03b4427ccf057debc83fc61ee102529"
        },
        {
          "url": "https://git.kernel.org/stable/c/de1f978c0f6ab42b28192d74dc59af52fdc76135"
        },
        {
          "url": "https://git.kernel.org/stable/c/ddbc5dc5a2e29b3934da09c1ba3c930fd8a40fd6"
        },
        {
          "url": "https://git.kernel.org/stable/c/a540a49fcca59d1c92c3a6462e67ca21676a88df"
        },
        {
          "url": "https://git.kernel.org/stable/c/23c53269f2baaedf2d92784290cb9ef6db2a3bce"
        }
      ],
      "title": "slip: remove slip_hangup() to fix use-after-free in slip_receive_buf()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90057",
    "datePublished": "2026-09-17T16:05:41.670Z",
    "dateReserved": "2026-09-11T19:38:34.784Z",
    "dateUpdated": "2026-10-19T08:57:14.597Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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