Look up another CVE · open CVE-2026-68143 in the interactive tracker
CVE-2026-68143
net: slip: serialize receive against buffer reallocation
Published 2026-08-10 (2 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-68143 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.101-1 | Update the kernel and reboot. Fixed in 6.12.101-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.6-1 | Update the kernel and reboot. Fixed in 7.1.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4745-1 · 2026-08-18 · text | 6.12.101-1~deb12u1 | Update the kernel and reboot. DLA-4745-1 shipped the fix on 2026-08-18, in 6.12.101-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
sl_realloc_bufs() replaces rbuff and updates buffsize while holding sl->lock. slip_receive_buf() reads those fields and writes through rbuff without holding the lock. An MTU change can therefore race with receive processing. An MTU shrink can expose the new smaller rbuff with the old larger bound, causing an out-of-bounds write. A receive callback which already loaded the old rbuff can instead continue writing after that buffer has been freed. Serialize receive processing with sl_realloc_bufs() by holding sl->lock while consuming each receive batch.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/net/slip/slip.c
- What this is
- NETWORKING DRIVERSMAINTAINERS section matched on drivers/net/ · netdev@vger.kernel.org · Maintained
- Kernel module
- slip
Check it on the machine
grep -wE 'CONFIG_SLHC|CONFIG_SLIP' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w slipPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- trixie, forky, sidMnot built on amd64/cloud-amd64, arm64/cloud-arm64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_SLHC, CONFIG_SLIP
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-10 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.14%, higher than 2.9% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.12 | 5.10.265 | 8180daf2b661 |
| 2.6.12 | 5.15.216 | 189a550eb7e1 |
| 2.6.12 | 6.1.183 | 1be09d175b62 |
| 2.6.12 | 6.6.148 | eb3836eab474 |
| 2.6.12 | 6.12.101 | 44401f7dd994 |
| 2.6.12 | 6.18.42 | 5d07b178bef5 |
| 2.6.12 | 7.1.6 | 0e37bbd6d617 |
| 2.6.12 | 7.2 | ee7f9bb9320a |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DLA-4745-1 | 2026-08-18 | bookworm 6.12.101-1~deb12u1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The bug is in the SLIP TTY line discipline; triggering the MTU shrink/realloc race requires SIOCSIFMTU/RTM_SETLINK (CAP_NET_ADMIN) on the host, so a single attacker must have local access even if SLIP frames arrive over a serial backhaul.
- AC:LAttack complexity, low
- An attacker with CAP_NET_ADMIN can concurrently hammer MTU changes via ioctl/rtnetlink and inject SLIP frames on the bound TTY/PTY, controlling both sides of the race without depending on uncontrollable timing.
- PR:LPrivileges required, low
- SIOCSIFMTU requires CAP_NET_ADMIN in the interface network namespace, obtainable by an unprivileged user via user namespaces; exploitation targets already-active SLIP links and does not repeat slip_open()'s init-namespace check.
- UI:NUser interaction, none
- No end-user or administrator interaction is required during exploitation once a SLIP interface is active; the attacker drives both MTU reallocation and receive processing directly.
- S:UScope, unchanged
- Heap corruption is confined to kernel SLIP receive buffers and adjacent kmalloc objects; impact is standard kernel memory corruption and local privilege escalation, not a cross-VM or sandbox boundary escape.
- C:HConfidentiality impact, high
- The race yields heap out-of-bounds writes and use-after-free writes on freed rbuff kmalloc objects; per kernel guidance, this class of memory corruption enables arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- Writing past the reallocated rbuff boundary or into a freed buffer corrupts adjacent heap metadata/objects, providing primitives for arbitrary kernel writes and control-flow hijacking.
- A:HAvailability impact, high
- Out-of-bounds and use-after-free corruption of kernel heap memory reliably causes kernel oops/panic during the race even when not fully weaponized for code execution.