CVE Intelligence
High

CVE-2026-81001 — slip: fix use-after-free in sl_sync()

In the Linux kernel, the following vulnerability has been resolved: slip: fix use-after-free in sl_sync() slip_devs[] stores bare net_device pointers and takes no reference on them. sl_sync() and sl_alloc() walk that table from slip_open() under rtnl_lock(), while an entry is dropped by sl_free_netdev(), which sl_setup() installs as dev->priv_destructor. priv_destructor is called from netdev_run_todo(), which deliberately runs with the RTNL semaphore released so that it can sleep while waiting for the device refcount to drop: /* Snapshot list, allow later requests */ list_replace_init(&net_todo_list, &list); __rtnl_unlock(); ... if (dev->priv_destructor) dev->priv_destructor(dev); /* slip_devs[i] = NULL */ if (dev->needs_free_netdev) free_netdev(dev); ... /* Free network device */ kobject_put(&dev->dev.kobj); So rtnl_lock() does not serialise slip_open() against the teardown at all. sl_sync() can load slip_devs[i] while the entry is still published and dereference it after netdev_run_todo() has run the destructor and released the device: CPU0 (slip_open) CPU1 (slip_close) unregister_netdev() rtnl_unlock() netdev_run_todo() __rtnl_unlock() rtnl_lock() sl_sync() dev = slip_devs[i] priv_destructor(dev) slip_devs[i] = NULL kobject_put(&dev->dev.kobj) /* dev is freed */ sl = netdev_priv(dev) if (sl->tty || sl->leased) /* use-after-free */ BUG: KASAN: use-after-free in sl_sync drivers/net/slip/slip.c:730 [inline] BUG: KASAN: use-after-free in slip_open+0xef4/0x1210 drivers/net/slip/slip.c:806 Read of size 1 at addr ffff8880712dac71 by task syz-executor.2/6506 CPU: 2 PID: 6506 Comm: syz-executor.2 Not tainted 6.1.134-syzkaller-00260-g0c8fc3469765 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: sl_sync drivers/net/slip/slip.c:730 [inline] slip_open+0xef4/0x1210 drivers/net/slip/slip.c:806 tty_ldisc_open+0xa2/0x120 drivers/tty/tty_ldisc.c:433 tty_set_ldisc+0x324/0x720 drivers/tty/tty_ldisc.c:564 tiocsetd drivers/tty/tty_io.c:2428 [inline] tty_ioctl+0x5f0/0x1530 drivers/tty/tty_io.c:2712 Allocated by task 6502: alloc_netdev_mqs+0x98/0xfe0 net/core/dev.c:10719 sl_alloc drivers/net/slip/slip.c:756 [inline] slip_open+0x36d/0x1210 drivers/net/slip/slip.c:817 tty_ldisc_open+0xa2/0x120 drivers/tty/tty_ldisc.c:433 tty_set_ldisc+0x324/0x720 drivers/tty/tty_ldisc.c:564 Freed by task 6497: device_release+0xa2/0x240 drivers/base/core.c:2507 kobject_put+0x179/0x280 lib/kobject.c:729 netdev_run_todo+0x6c8/0xef0 net/core/dev.c:10509 slip_close+0x166/0x1c0 drivers/net/slip/slip.c:906 tty_ldisc_close+0x113/0x1a0 drivers/tty/tty_ldisc.c:456 tty_ldisc_kill+0x94/0x160 drivers/tty/tty_ldisc.c:614 tty_ldisc_release+0xe3/0x2b0 drivers/tty/tty_ldisc.c:782 tty_release+0xbcc/0xe70 drivers/tty/tty_io.c:1860 Commit e58c19124189 ("slip: Fix use-after-free Read in slip_open") fixed a different source of stale entries - a device left in slip_devs[] after slip_open() freed it on the registration error path - and does not address this race, which is why the report survives it. Drop the entry from ndo_uninit instead. unregister_netdevice() calls ndo_uninit under RTNL, before the device is queued to netdev_run_todo(), so an entry that sl_sync() can still see while holding RTNL belongs to a device that cannot be freed until RTNL is dropped. sl_free_netdev() stays only for the slip_open() error path, where register_netdevice() may have failed before ndo_init and ndo_uninit is then not called either. Both running for the same device is harmless: the ---truncated---

Published Sep 11, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
—
No EPSS score.
Affects
Linux
Linux
CVSS base
7.8
High · 2 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux ≥ 5342b77c4123ba39f911d92a813295fb3bb21f69 and < 045e307ac21fbd735b789d8817b21be4d8ead054≥ 5342b77c4123ba39f911d92a813295fb3bb21f69 and < 87398cdec8bdf84096a8af4dbccdb04f1972f32c≥ 5342b77c4123ba39f911d92a813295fb3bb21f69 and < e93ace1f46177a4f7b5a8e5996606cdf77e1e890≥ 5342b77c4123ba39f911d92a813295fb3bb21f69 and < 70e20456bcbf7f3ae145bb96e5548f827a37c640≥ 5342b77c4123ba39f911d92a813295fb3bb21f69 and < a235b20972bbd98ca1fb127d6269434edc607f19≥ 5342b77c4123ba39f911d92a813295fb3bb21f69 and < 486577db807891d0f964fdf13c1640c7f54b0ad1≥ 5342b77c4123ba39f911d92a813295fb3bb21f69 and < d6f25e5bd777b05880da8673daf74a8419480545≥ 5342b77c4123ba39f911d92a813295fb3bb21f69 and < 2c4e7c42d77e78ad595dbb9e4b5886b58b45d89d
and 1 more version 2.6.32
Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
7.8 CVSS 3.1 High 1.8 5.9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
7.8 CVSS 3.1 High — — Linux via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67)

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
endpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · linux/linux
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 15, 2026
  • CVSS changed · 7.8
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Received
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 11, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

8 on the record

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

  • CVE-2026-99999 ipv4: validate checksum_start before completing checksum 13h
  • CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 13h
  • CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
  • CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
  • CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
  • CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No FIRST EPSS score.
  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No CWE classification.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-81001 is "slip: fix use-after-free in sl_sync()", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.

Sign in or create an account to comment and suggest corrections.