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CVE-2026-80735
ovpn: ensure socket is owned by ovpn before deref sk_user_data
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-2026-80735 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 | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.9-1 | Update the kernel and reboot. Fixed in 7.1.9-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Some subsystems, like BPF SOCKMAP, set sk_user_data without actually setting the encap_type. For this reason, we must make sure that the type is the one ovpn expects before dereferencing sk_user_data. Failing to do so may lead to out-of-bounds reads.
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/socket.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
- 7.3 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Lsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 5.8% 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 | 6.18.45 | 61fb3cca40ff |
| 6.16 | 7.1.9 | 43a31142e1d2 |
| 6.16 | 7.2 | 59aed1eb60d7 |
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 flaw is reached only via OVPN_CMD_PEER_NEW genetlink (local sendmsg/netlink syscall) that passes a UDP socket fd into ovpn_socket_new(); BPF SOCKMAP enrollment and ovpn setup are local kernel control paths, not remote packet handling.
- AC:LAttack complexity, low
- An attacker who can use OVPN netlink and BPF SOCKMAP fully controls creating a UDP socket, enrolling it in sockmap (sk_user_data set, encap_type left zero), and issuing PEER_NEW, deterministically hitting the bad cast on each attempt.
- PR:LPrivileges required, low
- All OVPN genetlink commands require GENL_ADMIN_PERM (CAP_NET_ADMIN), and BPF SOCKMAP enrollment needs bpf()/map privileges (CAP_BPF, often plus CAP_NET_ADMIN); both are obtainable by unprivileged users inside permitted user/network namespaces per CNA guidance.
- UI:NUser interaction, none
- No separate victim action is required; the same local actor creates the ovpn interface, enrolls their UDP socket in BPF SOCKMAP, and sends OVPN_CMD_PEER_NEW to trigger ovpn_socket_new() on that fd.
- S:UScope, unchanged
- Impact is confined to kernel memory misinterpretation within the host kernel security domain on VPN/offload nodes; it does not cross VM, container runtime, or IOMMU boundaries into another security authority.
- C:HConfidentiality impact, high
- When sk_user_data points to a BPF sk_psock (or similar non-ovpn owner) but encap_type is zero, ovpn_socket_new() casts it to struct ovpn_socket and reads ovpn_sock->ovpn, a type-confused out-of-bounds read of kernel memory per CNA OOB-read guidance.
- I:HIntegrity impact, high
- This is type confusion between foreign sk_user_data objects and struct ovpn_socket; CNA guidance rates type confusion High, and a mistaken ovpn_sock->ovpn match could drive ovpn_socket_hold() against the wrong layout, corrupting refcount-adjacent kernel fields.
- A:LAvailability impact, low
- The common path returns -EBUSY after the misread comparison, but the confused read and any mistaken hold can still provoke WARN/KASAN faults or refcount corruption on VPN gateways running ovpn offload with BPF sockmap, giving at least Low availability impact when uncertain.