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CVE-2026-68162
sctp: avoid auth_enable sysctl UAF 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-2026-68162 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
proc_sctp_do_auth() updates the SCTP control socket after changing net.sctp.auth_enable. The handler gets the per-net SCTP state from ctl->data, so an already opened sysctl file can still target a network namespace while that namespace is being torn down. SCTP previously registered its per-net sysctls from sctp_defaults_init(), while the control socket is created later from sctp_ctrlsock_init(). This exposed a window during initialization where auth_enable was writable before net->sctp.ctl_sock existed, and a teardown window where auth_enable stayed writable after inet_ctl_sock_destroy() had released the control socket. Move the per-net SCTP sysctl registration into sctp_ctrlsock_init() after sctp_ctl_sock_init() succeeds, and unregister the sysctl table before destroying the control socket in sctp_ctrlsock_exit(). If sysctl registration fails after the control socket was created, destroy the control socket in the same init path. Make sctp_sysctl_net_unregister() tolerate a missing header and clear the saved pointer so init-error and exit paths can safely share the unregister helper.
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
net/sctp/sysctl.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
- 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
- 0.20%, higher than 8.8% 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 |
|---|---|---|
| 5.4.290 | 5.4.292 | 19573dcddb88 |
| 5.10.234 | 5.10.266 | ceb7190b5c87 |
| 5.15.177 | 5.15.217 | fd66854a2266 |
| 6.1.125 | 6.1.184 | 158f3cc332dc |
| 6.6.72 | 6.6.151 | 66700c071967 |
| 6.12.10 | 6.12.101 | 626bda8cfe43 |
| 6.13 | 6.18.42 | be6aae9d1b91 |
| 6.13 | 7.1.6 | a50e73488e0b |
| 6.13 | 7.2 | f8d5e7846025 |
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 triggered only by writing the per-net sysctl net.sctp.auth_enable via /proc/sys (proc_sctp_do_auth); it is not reachable from SCTP packet receive, sockets, or other remote protocol paths.
- AC:LAttack complexity, low
- An attacker can open the sysctl file, concurrently destroy the target network namespace, and repeatedly write during teardown; pernet exit destroys ctl_sock before unregistering sysctls, and the attacker controls both sides of that race.
- PR:LPrivileges required, low
- Exploitation requires writing a mode 0644 sysctl in a network namespace; an unprivileged host user with CAP_NET_ADMIN via user namespaces can create a netns, become namespace root, and write net/sctp/auth_enable without init-namespace privileges.
- UI:NUser interaction, none
- No victim interaction is required beyond the attacker opening the sysctl and triggering namespace teardown in their own threads or processes.
- S:UScope, unchanged
- Impact is confined to kernel memory corruption and privilege escalation within the same host/kernel security domain; it does not cross VM, container, or IOMMU boundaries by itself.
- C:HConfidentiality impact, high
- proc_sctp_do_auth dereferences net->sctp.ctl_sock after inet_ctl_sock_destroy; lock_sock and sctp_sk(sk)->ep access freed socket/endpoint memory, a use-after-free that can disclose or infer heap contents.
- I:HIntegrity impact, high
- On a successful write, the handler sets sctp_sk(sk)->ep->auth_enable on a freed endpoint object, giving a controlled heap write primitive that can be developed into arbitrary kernel modification or code execution.
- A:HAvailability impact, high
- Use-after-free on the SCTP control socket/endpoint during sysctl processing can cause kernel oops/panic from lock_sock or ep access on freed memory, even when full exploitation is not attempted.