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CVE-2026-64076
netfilter: bridge: eb_tables: close module init race
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem net/bridge. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-64076 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 | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
sashiko reports for unrelated patch: Does the core ebtables initialization in ebtables.c suffer from a similar race? Once nf_register_sockopt() completes, the sockopts are exposed globally. sockopt has to be registered last, just like in ip/ip6/arptables.
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/bridge/netfilter/ebtables.c
- What this is
- NETFILTERMAINTAINERS section matched on net/*/netfilter/ · netfilter-devel@vger.kernel.org · Maintained
- Kernel module
- ebtables
Check it on the machine
grep -wE 'CONFIG_BRIDGE|CONFIG_BRIDGE_NF_EBTABLES|CONFIG_BRIDGE_NF_EBTABLES_LEGACY|CONFIG_NETFILTER' /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 ebtablesPrints 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 does not build this code in 2 releases. It does build it in 2 releases, so the answer depends on which release the machine runs.
- bookworm, trixiem
- forky, sidn
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- n
- not enabled on any flavour - this release does not build the code
- Build switches
- CONFIG_BRIDGE, CONFIG_BRIDGE_NF_EBTABLES, CONFIG_BRIDGE_NF_EBTABLES_LEGACY, CONFIG_NETFILTER
- Reads as
- all on means the file is compiled; any one off means it is not.
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
- 2026-07-19 (3 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
- 0.17%, higher than 6.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- net/bridge
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.13 | 6.18.34 | c647e2a21bbb |
| 5.13 | 7.0.11 | 02d999dc69b3 |
| 5.13 | 7.1 | 27414ff1b287 |
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
- Exploitation requires a local setsockopt/getsockopt syscall on a PF_INET socket; the vulnerable ebtables handlers are reached via ip_setsockopt → nf_setsockopt, not via remote bridge frame or network packet processing.
- AC:LAttack complexity, low
- The attacker can hammer concurrent setsockopt/getsockopt calls in a tight loop while waiting for or triggering ebtables module load, controlling the sockopt side of the init race window between nf_register_sockopt() and register_pernet_subsys().
- PR:LPrivileges required, low
- All ebtables sockopt entry points (do_ebt_set_ctl/do_ebt_get_ctl) gate on ns_capable(net->user_ns, CAP_NET_ADMIN), which is obtainable by an unprivileged user via user namespaces (unshare -Urn).
- UI:NUser interaction, none
- No victim interaction is required; exploitation is fully attacker-driven through concurrent syscalls during module initialization.
- S:UScope, unchanged
- Impact is confined to kernel memory and integrity within the same security authority; this is not a VM escape, sandbox breakout, or cross-tenant boundary crossing.
- C:HConfidentiality impact, high
- Before pernet registration, net_generic(net, 0) returns the net_generic.len field misinterpreted as a pointer, and list_for_each_entry on the resulting bogus ebt_pernet->tables can read unintended kernel memory before faulting.
- I:HIntegrity impact, high
- The same uninitialized net_generic lookup drives list traversal and subsequent ebtables table management paths (do_replace/do_update_counters) that perform kernel heap list operations and rule data writes against corrupted state.
- A:HAvailability impact, high
- Hitting the race window causes invalid pointer dereference during list iteration, producing a kernel oops/panic and denying system availability.