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CVE-2026-80520
ovpn: fix NULL dereference when killing missing key
Published 2026-08-26 (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-2026-80520 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_crypto_kill_key assumes both crypto slots are populated and dereferences each slot before checking it. That is not guaranteed: a peer can have only one installed key, and the kill path may be asked to remove a key that is not present. Read each slot once while holding the crypto state lock, check for NULL before looking at key_id, and only replace the slot that actually matches.
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/crypto.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
- 2026-08-26 (2 months ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.61%, higher than 48.1% 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 | 6.18.46 | a47a080d06ee |
| 6.16 | 7.1.10 | acf32a5dff08 |
| 6.16 | 7.2 | 41d44ac7a61e |
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
- The bug is reached from ovpn_encrypt_post during outbound VPN encryption over UDP/TCP; a remote authenticated OpenVPN peer can drive high-volume tunnel traffic that exhausts packet IDs and triggers ovpn_crypto_kill_key on internet-facing VPN concentrators.
- AC:LAttack complexity, low
- After a normal rekey leaves one key in slots[1] with slots[0] NULL, IV exhaustion deterministically calls ovpn_crypto_kill_key and the NULL dereference is reliable; a remote peer can sustain the encrypted traffic needed to reach the 32-bit packet-ID limit.
- PR:NPrivileges required, none
- Exploitation requires only an established OpenVPN data-channel session to an ovpn-offloaded interface, not local shell access, CAP_NET_ADMIN, or init-namespace root; no kernel configuration privileges are needed beyond being a connected VPN peer.
- UI:NUser interaction, none
- Triggering IV exhaustion and the subsequent key-kill path requires no victim user interaction beyond routine automated VPN traffic and key rotation already performed by the tunnel daemon.
- S:UScope, unchanged
- Impact is a kernel NULL-pointer fault and denial of service within the kernel network stack; it does not cross a security boundary such as guest-to-host escape or sandbox breakout.
- C:NConfidentiality impact, none
- This is a pure NULL pointer dereference when reading key_id from an unpopulated crypto slot; it does not expose kernel memory, leak pointers, or provide an arbitrary read primitive.
- I:NIntegrity impact, none
- The fault occurs on a NULL slot lookup and does not corrupt memory or enable arbitrary writes, code execution, or control-flow hijacking beyond the immediate crash.
- A:HAvailability impact, high
- The NULL dereference in ovpn_crypto_kill_key causes a kernel oops or panic when IV exhaustion triggers the key-kill path, fully denying service to the host and all VPN peers on that node.