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CVE-2026-74490
tipc: avoid use-after-free in poll trace queue dumps
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem net/tipc. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-74490 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 | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
TIPC socket tracepoints dump queue state through tipc_sk_dump(). Most queue-dump callsites already serialize that walk under the socket lock or sk->sk_lock.slock, but tipc_poll() calls trace_tipc_sk_poll(..., TIPC_DUMP_ALL, ...) without holding either lock. That lets the poll trace path reach tipc_list_dump() and backlog head/tail dumping while another context dequeues and frees an skb, leaving the trace helper dereferencing a stale queue entry. Stop the unlocked poll trace site from requesting queue dumps. Other queue dump trace callsites keep their existing output under the locking they already provide, while poll still emits the event itself without walking live queue members from an unlocked context.
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/tipc/socket.c
- What this is
- TIPC NETWORK LAYERMAINTAINERS section matched on net/tipc/ · netdev@vger.kernel.org · Maintained
- Kernel module
- tipc
Check it on the machine
grep -w CONFIG_TIPC /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 tipcPrints 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 as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sid, bookworm · linux-6.12m
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switch
- CONFIG_TIPC
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
- 2026-08-15 (2 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.46%, higher than 38.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/tipc
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.0 | 5.10.265 | 3cd57c6b210d |
| 5.0 | 5.15.216 | ae7fc8249708 |
| 5.0 | 6.1.183 | 78706367fe1b |
| 5.0 | 6.6.151 | d7940bb6a8e7 |
| 5.0 | 6.12.103 | 5e82beba4bc1 |
| 5.0 | 6.18.44 | bed792737b5f |
| 5.0 | 7.1.8 | ac2f787980fd |
| 5.0 | 7.2 | b4f1719dfea0 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | 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 UAF is a race between tipc_poll()'s unlocked trace queue walk and concurrent skb dequeue/free on the TIPC receive path; on cluster nodes a remote TIPC peer can supply the freeing side while poll/epoll runs on the victim socket processing that network traffic.
- AC:LAttack complexity, low
- The attacker controls both sides of the race by concurrently polling/epolling a TIPC socket while sending/receiving TIPC traffic (or having a remote peer deliver packets), and can repeat attempts until the unlocked head/tail dump overlaps skb free.
- PR:LPrivileges required, low
- Exploitation requires only an unprivileged local process with an AF_TIPC socket calling poll/epoll while TIPC traffic is processed; no real-root capability is needed beyond participation in an operational TIPC cluster where tracing may be enabled for diagnostics.
- UI:NUser interaction, none
- No end-user interaction is required; the race is triggered by normal daemon poll/epoll loops and incoming TIPC packet processing on cluster nodes.
- S:UScope, unchanged
- Impact is confined to kernel memory corruption and privilege boundaries within the host kernel; this is not a cross-VM or cross-container sandbox escape scenario.
- C:HConfidentiality impact, high
- The bug is a use-after-free where tipc_list_dump()/tipc_skb_dump() dereference head/tail skbs after concurrent dequeue/kfree, enabling reads of freed skb and message memory usable for kernel information disclosure.
- I:HIntegrity impact, high
- UAF on skb queue entries can be leveraged with heap grooming for arbitrary kernel writes and control-flow hijack, not merely a benign crash, because freed skbs can be reallocated under attacker-influenced TIPC traffic.
- A:HAvailability impact, high
- Accessing freed skbs from the poll trace path can cause kernel oops/panic or hang during tipc_skb_dump(), and repeated triggering yields reliable denial of service on affected cluster nodes.