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CVE-2026-68144
phonet: pep: fix use-after-free in pep_get_sb()
Published 2026-08-10 (2 months ago) by the Linux kernel CNA. Subsystem net/phonet. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-68144 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
pep_get_sb() doesn't consider that pskb_may_pull() might have relocated the skb data, and continue to access the older pointer, causing UAF. Reproduced under KASAN: BUG: KASAN: slab-use-after-free in pep_get_sb+0x234/0x3b0 Read of size 1 at addr ff11000105510f50 by task repro/157 pep_get_sb+0x234/0x3b0 pipe_handler_do_rcv+0x5f7/0xa10 pep_do_rcv+0x203/0x410 __sk_receive_skb+0x471/0x4a0 phonet_rcv+0x5b3/0x6c0 __netif_receive_skb+0xcc/0x1d0 Refetch the header with skb_header_pointer() after pskb_may_pull(), so the possibly stale pointer is no longer dereferenced. There are better ways to solve this, but, this is the less instrusive one.
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.
net/phonet/pep.c
- What this is
- PHONET PROTOCOLMAINTAINERS section matched on net/phonet/ · Supported
- Kernel module
- pn_pep
Check it on the machine
grep -w CONFIG_PHONET /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 pn_pepPrints 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.
- bookworm, trixie, forky, sid, 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 switch
- CONFIG_PHONET
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
- 9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.54%, higher than 44.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/phonet
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.28 | 5.10.265 | c4a52cb4da8d |
| 2.6.28 | 5.15.216 | df198743859f |
| 2.6.28 | 6.1.183 | 1d81e19fc57a |
| 2.6.28 | 6.6.148 | 8d931a75a38b |
| 2.6.28 | 6.12.101 | 17f78c0c0d41 |
| 2.6.28 | 6.18.42 | a48a889b60f7 |
| 2.6.28 | 7.1.6 | 25e3641beb51 |
| 2.6.28 | 7.2 | 0f71f852a96a |
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:NAttack vector, network
- The bug is hit in phonet_rcv() via __netif_receive_skb() when processing inbound Phonet pipe packets on a netdev; on modem-equipped phones this path is reachable from the cellular/BT-facing modem link without local access.
- AC:LAttack complexity, low
- The attacker fully controls crafted TLV sb_len values in Phonet pipe messages to deterministically force pskb_may_pull() skb head reallocation; no race or victim-specific state beyond an existing/connecting pipe socket is required.
- PR:NPrivileges required, none
- Exploitation requires only delivering a malformed Phonet packet to a listening/connecting pipe endpoint; phonet_rcv() performs no authentication or capability checks before delivering to pep_do_rcv() and pep_get_sb().
- UI:NUser interaction, none
- No end-user action is needed; triggering only requires a background phonet pipe listener or an in-progress connect/accept on affected Nokia/modem platforms where phonet daemons run continuously.
- S:UScope, unchanged
- Impact is confined to kernel memory/process integrity on the affected host; successful exploitation yields local privilege escalation within the same kernel security domain, not a cross-VM or cross-container boundary escape.
- C:HConfidentiality impact, high
- Confirmed slab use-after-free read in pep_get_sb(); stale post-realloc pointer dereference can leak adjacent heap contents and is a standard primitive for arbitrary kernel memory disclosure.
- I:HIntegrity impact, high
- Use-after-free on skb header memory enables heap grooming and control of freed object contents, providing a well-established path to arbitrary kernel writes and code execution beyond the immediate one-byte read.
- A:HAvailability impact, high
- KASAN reproduced a slab use-after-free oops in pep_get_sb() during packet receive; even without full exploit development, malformed Phonet pipe packets can reliably panic or hang the kernel on affected systems.