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CVE-2026-72383
sctp: fix addr_wq_timer race in sctp_free_addr_wq()
Published 2026-08-15 (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-2026-72383 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
sctp_free_addr_wq() previously removed addr_wq_timer using timer_delete() while holding addr_wq_lock. However, timer_delete() does not guarantee that a currently running timer handler has completed. This allows a race with sctp_addr_wq_timeout_handler(), where the handler may still run after addr_waitq has been freed, acquire addr_wq_lock, and access freed memory, leading to a use-after-free. Fix this by calling timer_shutdown_sync() before taking addr_wq_lock. This guarantees that any in-flight timer handler has finished and prevents the timer from being re-armed during teardown, making subsequent cleanup safe.
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, sidm
- 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
- 2026-08-15 (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
- 0.16%, higher than 4.9% 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 |
|---|---|---|
| 3.7 | 6.18.40 | a8323fb2ab6c |
| 3.7 | 7.1.5 | c3e5cac47519 |
| 3.7 | 7.2 | 976c19de0f22 |
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 UAF is in sctp_free_addr_wq() during per-network-namespace SCTP teardown when a net namespace is destroyed; reaching it requires local syscalls (unshare/exit, SCTP socket/bind/setsockopt, rtnetlink address changes), not remote SCTP packet receive paths.
- AC:LAttack complexity, low
- The attacker controls both sides of the race by creating a netns with SCTP AUTO_ASCONF sockets, queueing address events that arm addr_wq_timer (~500ms), and concurrently destroying that namespace; timer_delete() does not wait for sctp_addr_wq_timeout_handler(), so the UAF is reliably winnable.
- PR:LPrivileges required, low
- An unprivileged local user can obtain CAP_NET_ADMIN in a new user+network namespace via unshare, bind an SCTP socket to INADDR_ANY, enable SCTP_AUTO_ASCONF, churn interface addresses to populate addr_waitq, and destroy the namespace; container tenants can trigger the same netns teardown without init-namespace root.
- UI:NUser interaction, none
- Exploitation is fully attacker-driven through scripted namespace create/configure/destroy and concurrent threads; no victim must mount filesystems, open files, or take any discretionary action beyond the attacker's own setup.
- S:UScope, unchanged
- The bug is kernel heap use-after-free of sctp_sockaddr_entry during netns teardown; impact is host kernel memory corruption and privilege escalation within the same kernel security authority, not a VM/hypervisor or IOMMU boundary crossing.
- C:HConfidentiality impact, high
- sctp_addr_wq_timeout_handler() may walk addr_waitq and dereference sctp_sockaddr_entry fields after sctp_free_addr_wq() kfree()'s those entries; UAF on freed heap objects enables kernel memory disclosure and supports further exploitation primitives.
- I:HIntegrity impact, high
- The timer handler calls sctp_asconf_mgmt() on corrupted addrw pointers (address family, sockaddr, state), driving ASCONF add/delete processing on freed memory; UAF heap corruption is exploitable for arbitrary kernel write and potential code execution.
- A:HAvailability impact, high
- Use-after-free in sctp_addr_wq_timeout_handler() during list iteration, socket locking, and sctp_asconf_mgmt() can cause kernel oops or panic from accesses to freed sctp_sockaddr_entry memory, even when full exploitation is not attempted.