{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-81001", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.812Z", "datePublished": "2026-09-11T19:42:54.846Z", "dateUpdated": "2026-10-19T08:46:25.639Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:46:25.639Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nslip: fix use-after-free in sl_sync()\n\nslip_devs[] stores bare net_device pointers and takes no reference on\nthem. sl_sync() and sl_alloc() walk that table from slip_open() under\nrtnl_lock(), while an entry is dropped by sl_free_netdev(), which\nsl_setup() installs as dev->priv_destructor.\n\npriv_destructor is called from netdev_run_todo(), which deliberately\nruns with the RTNL semaphore released so that it can sleep while waiting\nfor the device refcount to drop:\n\n\t/* Snapshot list, allow later requests */\n\tlist_replace_init(&net_todo_list, &list);\n\n\t__rtnl_unlock();\n\t...\n\t\tif (dev->priv_destructor)\n\t\t\tdev->priv_destructor(dev);\t/* slip_devs[i] = NULL */\n\t\tif (dev->needs_free_netdev)\n\t\t\tfree_netdev(dev);\n\t\t...\n\t\t/* Free network device */\n\t\tkobject_put(&dev->dev.kobj);\n\nSo rtnl_lock() does not serialise slip_open() against the teardown at\nall. sl_sync() can load slip_devs[i] while the entry is still published\nand dereference it after netdev_run_todo() has run the destructor and\nreleased the device:\n\n CPU0 (slip_open) CPU1 (slip_close)\n unregister_netdev()\n rtnl_unlock()\n netdev_run_todo()\n __rtnl_unlock()\n rtnl_lock()\n sl_sync()\n dev = slip_devs[i]\n priv_destructor(dev)\n slip_devs[i] = NULL\n kobject_put(&dev->dev.kobj)\n /* dev is freed */\n sl = netdev_priv(dev)\n if (sl->tty || sl->leased) /* use-after-free */\n\n BUG: KASAN: use-after-free in sl_sync drivers/net/slip/slip.c:730 [inline]\n BUG: KASAN: use-after-free in slip_open+0xef4/0x1210 drivers/net/slip/slip.c:806\n Read of size 1 at addr ffff8880712dac71 by task syz-executor.2/6506\n\n CPU: 2 PID: 6506 Comm: syz-executor.2 Not tainted 6.1.134-syzkaller-00260-g0c8fc3469765 #0\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014\n Call Trace:\n sl_sync drivers/net/slip/slip.c:730 [inline]\n slip_open+0xef4/0x1210 drivers/net/slip/slip.c:806\n tty_ldisc_open+0xa2/0x120 drivers/tty/tty_ldisc.c:433\n tty_set_ldisc+0x324/0x720 drivers/tty/tty_ldisc.c:564\n tiocsetd drivers/tty/tty_io.c:2428 [inline]\n tty_ioctl+0x5f0/0x1530 drivers/tty/tty_io.c:2712\n\n Allocated by task 6502:\n alloc_netdev_mqs+0x98/0xfe0 net/core/dev.c:10719\n sl_alloc drivers/net/slip/slip.c:756 [inline]\n slip_open+0x36d/0x1210 drivers/net/slip/slip.c:817\n tty_ldisc_open+0xa2/0x120 drivers/tty/tty_ldisc.c:433\n tty_set_ldisc+0x324/0x720 drivers/tty/tty_ldisc.c:564\n\n Freed by task 6497:\n device_release+0xa2/0x240 drivers/base/core.c:2507\n kobject_put+0x179/0x280 lib/kobject.c:729\n netdev_run_todo+0x6c8/0xef0 net/core/dev.c:10509\n slip_close+0x166/0x1c0 drivers/net/slip/slip.c:906\n tty_ldisc_close+0x113/0x1a0 drivers/tty/tty_ldisc.c:456\n tty_ldisc_kill+0x94/0x160 drivers/tty/tty_ldisc.c:614\n tty_ldisc_release+0xe3/0x2b0 drivers/tty/tty_ldisc.c:782\n tty_release+0xbcc/0xe70 drivers/tty/tty_io.c:1860\n\nCommit e58c19124189 (\"slip: Fix use-after-free Read in slip_open\") fixed\na different source of stale entries - a device left in slip_devs[] after\nslip_open() freed it on the registration error path - and does not\naddress this race, which is why the report survives it.\n\nDrop the entry from ndo_uninit instead. unregister_netdevice() calls\nndo_uninit under RTNL, before the device is queued to netdev_run_todo(),\nso an entry that sl_sync() can still see while holding RTNL belongs to a\ndevice that cannot be freed until RTNL is dropped. sl_free_netdev()\nstays only for the slip_open() error path, where register_netdevice()\nmay have failed before ndo_init and ndo_uninit is then not called\neither. Both running for the same device is harmless: the\n---truncated---" } ], "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 only via local TTY syscalls: open(\"/dev/ptmx\") then ioctl(TIOCSETD, N_SLIP) into tty_ioctl→tiocsetd→tty_set_ldisc→slip_open→sl_sync, raced with close()→slip_close→unregister_netdev. sl_sync() is not on the packet-receive path, so the vector is Local rather than Network or Physical.\nAC:L - The attacker controls both sides of the race, looping open(ptmx)+TIOCSETD(N_SLIP)+close() on several threads as in the syzkaller reproducer. netdev_run_todo() drops RTNL during attacker-initiated teardown, so winning the window does not depend on victim state or other uninfluenceable timing.\nPR:L - slip_open() requires capable(CAP_NET_ADMIN), which checks init_user_ns and is not granted by unshare -Urn. CAP_NET_ADMIN in the initial user namespace is still routinely delegated to non-root container and network workloads (Docker/K8s --cap-add=NET_ADMIN, CNI/VPN sidecars) without full host root, so privileges required are Low.\nUI:N - The attacker performs every step—opening PTYs, attaching N_SLIP, and closing fds—in its own processes. No separate victim user or administrator action is required at exploit time.\nS:U - The UAF corrupts a host-kernel net_device from alloc_netdev() and remains inside that kernel’s security authority. Impact is standard local privilege escalation, not a VM escape or IOMMU/DMA boundary bypass.\nC:H - sl_sync() dereferences a freed net_device and its embedded struct slip (netdev_priv). Per kernel CNA guidance a use-after-free lets the attacker control the freed object via heap spray, yielding an arbitrary kernel read primitive.\nI:H - After the UAF load, sl_sync() may call dev_close() on the freed or reused net_device, exercising netdev_ops and related kernel state. That is a use-after-free of an object with function pointers, enabling arbitrary writes and control-flow hijacking.\nA:H - Use-after-free of the SLIP net_device causes a kernel oops or panic even when not fully exploited; KASAN reported a slab-use-after-free in sl_sync() on the syzkaller reproducer." } ] } ], "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": "045e307ac21fbd735b789d8817b21be4d8ead054", "status": "affected", "versionType": "git" }, { "version": "5342b77c4123ba39f911d92a813295fb3bb21f69", "lessThan": "87398cdec8bdf84096a8af4dbccdb04f1972f32c", "status": "affected", "versionType": "git" }, { "version": "5342b77c4123ba39f911d92a813295fb3bb21f69", "lessThan": "e93ace1f46177a4f7b5a8e5996606cdf77e1e890", "status": "affected", "versionType": "git" }, { "version": "5342b77c4123ba39f911d92a813295fb3bb21f69", "lessThan": "70e20456bcbf7f3ae145bb96e5548f827a37c640", "status": "affected", "versionType": "git" }, { "version": "5342b77c4123ba39f911d92a813295fb3bb21f69", "lessThan": "a235b20972bbd98ca1fb127d6269434edc607f19", "status": "affected", "versionType": "git" }, { "version": "5342b77c4123ba39f911d92a813295fb3bb21f69", "lessThan": "486577db807891d0f964fdf13c1640c7f54b0ad1", "status": "affected", "versionType": "git" }, { "version": "5342b77c4123ba39f911d92a813295fb3bb21f69", "lessThan": "d6f25e5bd777b05880da8673daf74a8419480545", "status": "affected", "versionType": "git" }, { "version": "5342b77c4123ba39f911d92a813295fb3bb21f69", "lessThan": "2c4e7c42d77e78ad595dbb9e4b5886b58b45d89d", "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": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.221", "lessThanOrEqual": "5.15.*", "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": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "5.10.270" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.32", "versionEndExcluding": "5.15.221" }, { "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": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.32", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.32", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.32", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/045e307ac21fbd735b789d8817b21be4d8ead054" }, { "url": "https://git.kernel.org/stable/c/87398cdec8bdf84096a8af4dbccdb04f1972f32c" }, { "url": "https://git.kernel.org/stable/c/e93ace1f46177a4f7b5a8e5996606cdf77e1e890" }, { "url": "https://git.kernel.org/stable/c/70e20456bcbf7f3ae145bb96e5548f827a37c640" }, { "url": "https://git.kernel.org/stable/c/a235b20972bbd98ca1fb127d6269434edc607f19" }, { "url": "https://git.kernel.org/stable/c/486577db807891d0f964fdf13c1640c7f54b0ad1" }, { "url": "https://git.kernel.org/stable/c/d6f25e5bd777b05880da8673daf74a8419480545" }, { "url": "https://git.kernel.org/stable/c/2c4e7c42d77e78ad595dbb9e4b5886b58b45d89d" } ], "title": "slip: fix use-after-free in sl_sync()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-81001", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:22:06.585249Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:38.316Z" } } ] } }