CVE-2026-90057 (GCVE-0-2026-90057)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:05 – Updated: 2026-09-18 17:52
VLAI
Title
slip: remove slip_hangup() to fix use-after-free in slip_receive_buf()
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().
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 5342b77c4123ba39f911d92a813295fb3bb21f69 , < 9a3b1edff1ecb47d323f2506b3ffc22178acd1c6 (git)
Affected: 5342b77c4123ba39f911d92a813295fb3bb21f69 , < a2dbac3fb03b4427ccf057debc83fc61ee102529 (git)
Affected: 5342b77c4123ba39f911d92a813295fb3bb21f69 , < de1f978c0f6ab42b28192d74dc59af52fdc76135 (git)
Affected: 5342b77c4123ba39f911d92a813295fb3bb21f69 , < ddbc5dc5a2e29b3934da09c1ba3c930fd8a40fd6 (git)
Affected: 5342b77c4123ba39f911d92a813295fb3bb21f69 , < a540a49fcca59d1c92c3a6462e67ca21676a88df (git)
Affected: 5342b77c4123ba39f911d92a813295fb3bb21f69 , < 23c53269f2baaedf2d92784290cb9ef6db2a3bce (git)
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Linux Linux Affected: 2.6.32
Unaffected: 0 , < 2.6.32 (semver)
Unaffected: 6.1.188 , ≤ 6.1.* (semver)
Unaffected: 6.6.157 , ≤ 6.6.* (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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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
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              "version": "7.2.6",
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              "version": "7.3-rc1",
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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."
            }
          ]
        }
      ],
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        "dateUpdated": "2026-09-18T17:52:47.908Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/9a3b1edff1ecb47d323f2506b3ffc22178acd1c6"
        },
        {
          "url": "https://git.kernel.org/stable/c/a2dbac3fb03b4427ccf057debc83fc61ee102529"
        },
        {
          "url": "https://git.kernel.org/stable/c/de1f978c0f6ab42b28192d74dc59af52fdc76135"
        },
        {
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          "url": "https://git.kernel.org/stable/c/a540a49fcca59d1c92c3a6462e67ca21676a88df"
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        {
          "url": "https://git.kernel.org/stable/c/23c53269f2baaedf2d92784290cb9ef6db2a3bce"
        }
      ],
      "title": "slip: remove slip_hangup() to fix use-after-free in slip_receive_buf()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90057",
    "datePublished": "2026-09-17T16:05:41.670Z",
    "dateReserved": "2026-09-11T19:38:34.784Z",
    "dateUpdated": "2026-09-18T17:52:47.908Z",
    "state": "PUBLISHED"
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        "cveTags": [],
        "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()."
          }
        ],
        "id": "CVE-2026-90057",
        "lastModified": "2026-09-18T18:17:40.053",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.8,
              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-09-17T17:16:54.310",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/23c53269f2baaedf2d92784290cb9ef6db2a3bce"
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          },
          {
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            "url": "https://git.kernel.org/stable/c/ddbc5dc5a2e29b3934da09c1ba3c930fd8a40fd6"
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          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/de1f978c0f6ab42b28192d74dc59af52fdc76135"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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