CVE-2026-99031
Published Oct 23, 2026
Description
In the Linux kernel, the following vulnerability has been resolved: net: bridge: avoid recursive multicast port cleanup br_multicast_sg_del_exclude_ports() removes automatically added STAR_EXCL port groups by calling br_multicast_del_pg(). For S,G entries, that deletion calls back into br_multicast_sg_del_exclude_ports(), so a large number of STAR_EXCL ports consumes one kernel stack frame per port and can hit the stack guard page. Keep the complete port-group deletion path for cleanup, but suppress the S,G exclude-port cleanup while that helper is already walking the same entry. Normal deletion callers retain the existing behavior.
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References
Other References
https://git.kernel.org/stable/c/2fb87c6025f90191516bee3ce14b42eb3e1cfed7
https://git.kernel.org/stable/c/5158353121bae4f552cb677ce8c5c3ef52f93a0d
https://git.kernel.org/stable/c/695a5a4c69c922d9296b2d7ad5f1ce8c6858fc64
https://git.kernel.org/stable/c/7931fb9181421953f3133b408b0f2e2b8dd68b61
https://git.kernel.org/stable/c/d109141ba14652146089ef78b32d5e4d5285ebad
Frequently Asked Questions
What is CVE-2026-99031? +
In the Linux kernel, the following vulnerability has been resolved:
net: bridge: avoid recursive multicast port cleanup
br_multicast_sg_del_exclude_ports() removes automatically added STAR_EXCL
port groups by calling br_multicast_del_pg(). For S,G entries, that
deletion calls back into br_multicast_sg_del_exclude_ports(), so a large
number of STAR_EXCL ports consumes one kernel stack frame per port and can
hit the stack guard page.
Keep the complete port-group deletion path for cleanup, but suppress the
S,G exclude-port cleanup while that helper is already walking the same
entry. Normal deletion callers retain the existing behavior.
How do I check if I'm vulnerable to CVE-2026-99031? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.