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CVE-2026-80753
ovpn: run deferred work on a module-owned workqueue
Published 2026-09-03 (2 months ago) by the Linux kernel CNA. Subsystem drivers/net. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-80753 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.10-1 | Update the kernel and reboot. Fixed in 7.1.10-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
ovpn queues several work items whose callbacks execute module text. These works currently run on the global system workqueues, so module exit has no driver-owned drain point that guarantees the callbacks have fully returned before the module text can be freed. Object references protect the objects used by the callbacks, but they do not prove that a workqueue function has returned. In particular, a worker can drop the final reference that unblocks device teardown while it is still executing ovpn code. Add a module-owned workqueue and queue all ovpn work items on it. During module exit, unregister rtnl and netlink first, flush the workqueue so ordinary ovpn workers finish, run the final RCU barrier, and destroy the workqueue last. This keeps the workqueue available for cleanup work queued from RCU callbacks, while ensuring no ovpn work item can outlive the module text. The per-device delayed keepalive work remains explicitly disabled during netdev teardown (disable_delayed_work_sync in ndo_uninit), since flush_workqueue does not flush delayed work that is still only pending on its timer.
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.
drivers/net/ovpn/main.c
drivers/net/ovpn/ovpnpriv.h
drivers/net/ovpn/peer.c
drivers/net/ovpn/tcp.c
- What this is
- OPENVPN DATA CHANNEL OFFLOADMAINTAINERS section matched on drivers/net/ovpn/ · openvpn-devel@lists.sourceforge.net · Supported
- Kernel module
- ovpn
Check it on the machine
grep -w CONFIG_OVPN /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 ovpnPrints 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 with an answer 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. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidm
- ?
- not established - no Makefile entry for the affected file
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switch
- CONFIG_OVPN
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
- 2026-09-03 (2 months ago)source
- CVSS
- 8.4 high
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.19%, higher than 8.4% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/net
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.16 | 6.18.50 | b5fe67111e63 |
| 6.16 | 7.1.10 | bbe81f40582d |
| 6.16 | 7.2 | e9714db80417 |
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 module-text UAF is triggered in ovpn_cleanup() during local rmmod/module exit; although defer_del_work, keepalive_work, and tcp_tx_work are queued from remote TCP VPN traffic via ovpn_tcp_rcv() and ovpn_tcp_write_space(), there is no network-reachable path into module_exit itself.
- AC:LAttack complexity, low
- Per CNA driver-removal UAF precedent, an attacker controls the work side by sustaining remote OpenVPN transport traffic (malformed TCP frames, transport errors, or write-space callbacks) while root or package-manager rmmod during upgrade races unpooled system_wq workers still executing ovpn module callbacks.
- PR:NPrivileges required, none
- Privileged module unload opens the window, but concurrent execution of ovpn work on system_percpu_wq is driven by remote VPN peers sending transport frames to configured offload tunnels; no Linux account, CAP_NET_ADMIN, or CAP_SYS_MODULE on the victim is required for that half.
- UI:NUser interaction, none
- No victim user interaction beyond normal VPN gateway operation and routine kernel/module maintenance; remote peers autonomously schedule ovpn work items when sending transport frames to established offload tunnels.
- S:UScope, unchanged
- Freed module-text UAF corrupts kernel code and data within the same host security boundary; impact is standard in-kernel privilege escalation or panic, not VM escape, container boundary crossing, or IOMMU bypass.
- C:HConfidentiality impact, high
- Use-after-free of ovpn module .text lets freed page contents be attacker-influenced via heap or page reuse while the worker still executes callback instructions, yielding arbitrary kernel memory read primitives per UAF guidance.
- I:HIntegrity impact, high
- Executing freed module text provides a control-flow hijack surface into kernel context; combined with slab spraying over recycled module pages this enables arbitrary kernel write and local privilege escalation beyond mere denial of service.
- A:HAvailability impact, high
- Running ovpn workqueue handlers after module text is unmapped reliably causes kernel oops or panic from invalid instruction fetches, and repeated rmmod races against active VPN traffic yield repeatable denial of service on internet-facing gateways.