CVE-2026-90114

What the bug is

A pair of descending VLAN and tunnel IDs can pass the tunnel range span check. The VLAN subtraction produces a negative int, which is converted to unsigned when compared with the u32 tunnel ID subtraction. It can therefore equal the wrapped tunnel ID delta. The range loop then performs no iterations. Since the batched notification handling added a post-loop error check, this leaves err uninitialized and makes the request's return value unpredictable. Reject descending VLAN ranges before comparing the spans. Valid ascending and single-entry ranges remain unchanged, while malformed descending ranges consistently return -EINVAL. This issue was found by a static analysis checker and confirmed by manual source review.

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/br_netlink_tunnel.c

What this is

ETHERNET BRIDGEMAINTAINERS section matched on net/bridge/ · bridge@lists.linux.dev · Maintained

Kernel module

bridge

Check it on the machine

grep -w CONFIG_BRIDGE /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 bridge

Prints 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, sid, bookworm · linux-6.12m

m

a loadable module on every flavour - check lsmod, can be blacklisted

Build switch

CONFIG_BRIDGE

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

2026-09-17 (31 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.22%, higher than 11.2% 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
5.9	5.10.270	1181f6bad009
5.9	5.15.221	5a8e0e3a18b5
5.9	6.1.188	0874a6d52750
5.9	6.6.157	4b0f5b25f114
5.9	6.12.110	bd741b819ff1
5.9	6.18.52	c0444d7499f1
5.9	7.2.6	434849b21ef5
5.9	7.3	b74a072d8fb7

Debian advisories