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CVE-2026-68161
sctp: close UDP tunnel sockets during netns teardown
Published 2026-08-10 (2 months ago) by the Linux kernel CNA. Subsystem net/sctp. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-68161 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-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. 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
proc_sctp_do_udp_port() starts per-net SCTP UDP tunneling sockets when net.sctp.udp_port is set, and stops/restarts them when the sysctl value changes. The netns exit path does not stop these sockets, so a namespace can be torn down while its SCTP UDP tunnel sockets are still installed. Close the UDP tunnel sockets from sctp_ctrlsock_exit() after unregistering the per-net sysctl table. This prevents new sysctl writes from racing in while the sockets are being released, and closes the sockets before the control socket is destroyed.
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/sctp/protocol.c
- What this is
- SCTP PROTOCOLMAINTAINERS section matched on net/sctp/ · linux-sctp@vger.kernel.org · Maintained
- Kernel module
- sctp
Check it on the machine
grep -w CONFIG_IP_SCTP /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 sctpPrints 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_IP_SCTP
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
- 0.66%, higher than 50.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/sctp
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.11 | 6.1.189 | c29affd44e67 |
| 5.11 | 6.6.151 | c6eb2d615210 |
| 5.11 | 6.12.101 | 8ff78591d309 |
| 5.11 | 6.18.42 | 3bf0e349cbb4 |
| 5.11 | 7.1.6 | 37ff9794be48 |
| 5.11 | 7.2 | ffb2bd7ade36 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | 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
- Stale SCTP UDP tunnel sockets left installed after netns teardown still receive remote SCTP-over-UDP (RFC 6951) on the configured net.sctp.udp_port; packets enter sctp_udp_rcv→sctp_rcv in softirq and touch freed per-net SCTP/UDP state.
- AC:LAttack complexity, low
- An attacker can repeatedly race namespace deletion against SCTP-over-UDP traffic they send or receive, controlling both teardown timing and packet delivery; no attacker-uncontrollable memory layout or rare kernel config is required beyond SCTP being enabled.
- PR:NPrivileges required, none
- On SCTP-over-UDP deployments where net.sctp.udp_port is already configured, any remote SCTP peer needs no credentials on the target; alternatively an unprivileged local user obtains CAP_NET_ADMIN via user namespaces to set udp_port and destroy the namespace.
- UI:NUser interaction, none
- Exploitation requires only attacker-driven SCTP-over-UDP traffic and namespace lifecycle events (e.g., container restart); no victim must mount a filesystem, open a file, or take any separate interactive action.
- S:UScope, unchanged
- Impact is host-kernel slab use-after-free and memory corruption within the same OS security authority; it does not cross VM, IOMMU, or sandbox boundaries to affect a separate security domain.
- C:HConfidentiality impact, high
- Use-after-free of struct net and SCTP UDP tunnel socket state lets an attacker influence freed slab contents and obtain arbitrary kernel memory read primitives through subsequent SCTP/UDP lookups and socket processing.
- I:HIntegrity impact, high
- The UAF enables heap grooming and reuse of freed per-net/socket objects in SCTP/UDP handlers, supporting arbitrary kernel writes and control-flow hijack typical of slab use-after-free exploitation.
- A:HAvailability impact, high
- Dereferencing SCTP/UDP tunnel sockets and per-net state after netns free causes slab use-after-free detections, kernel oops, or panic; even unexploited UAF commonly crashes or hangs the host.