{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90057","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.784Z","datePublished":"2026-09-17T16:05:41.670Z","dateUpdated":"2026-09-18T17:52:47.908Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-18T17:52:47.908Z"},"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->ops->hangup() while holding only\na read lock on tty->ldisc_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->ldisc_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":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"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→tty_insert_flip_string_and_push_buffer→flush_to_ldisc→tty_port_default_receive_buf→slip_receive_buf, while close() of that master runs pty_close→tty_vhangup→tty_ldisc_hangup→slip_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()'s read lock) concurrently with close()→pty_close→tty_vhangup→slip_hangup, which tty_ldisc_hangup() also invokes under only a read lock. Because hangup() is not serialized by ldisc_sem's write side, the attacker creates and retries the race.\nPR:L - Attaching N_SLIP requires slip_open()'s capable(CAP_NET_ADMIN) check, which is ns_capable(&init_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()→tty_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->disc_data without an RCU read-side critical section, then reads sl->magic and sl->dev after slip_hangup()→slip_close()→unregister_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(&sl->lock) and slip_unesc() writes sl->rbuff[sl->rcount++] and sl->flags 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."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/slip/slip.c"],"versions":[{"version":"5342b77c4123ba39f911d92a813295fb3bb21f69","lessThan":"9a3b1edff1ecb47d323f2506b3ffc22178acd1c6","status":"affected","versionType":"git"},{"version":"5342b77c4123ba39f911d92a813295fb3bb21f69","lessThan":"a2dbac3fb03b4427ccf057debc83fc61ee102529","status":"affected","versionType":"git"},{"version":"5342b77c4123ba39f911d92a813295fb3bb21f69","lessThan":"de1f978c0f6ab42b28192d74dc59af52fdc76135","status":"affected","versionType":"git"},{"version":"5342b77c4123ba39f911d92a813295fb3bb21f69","lessThan":"ddbc5dc5a2e29b3934da09c1ba3c930fd8a40fd6","status":"affected","versionType":"git"},{"version":"5342b77c4123ba39f911d92a813295fb3bb21f69","lessThan":"a540a49fcca59d1c92c3a6462e67ca21676a88df","status":"affected","versionType":"git"},{"version":"5342b77c4123ba39f911d92a813295fb3bb21f69","lessThan":"23c53269f2baaedf2d92784290cb9ef6db2a3bce","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/slip/slip.c"],"versions":[{"version":"2.6.32","status":"affected"},{"version":"0","lessThan":"2.6.32","status":"unaffected","versionType":"semver"},{"version":"6.1.188","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.157","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.110","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.52","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.6","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.32","versionEndExcluding":"7.3-rc1"}]}]}],"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"}}}}