CVE-2026-80739: In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: TC, Check if flow is PEER before acquiring devcom lock In case __mlx5e_add_fdb

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: TC, Check if flow is PEER before acquiring devcom lock In case __mlx5e_add_fdb_

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: TC, Check if flow is PEER before acquiring devcom lock In case __mlx5e_add_fdb_flow() fails in lower levels, the flow is deleted via mlx5e_tc_del_flow(), and mlx5e_tc_del_flow() is acquiring ESW devcom lock without condition. In addition, in case of peer_flow, __mlx5e_add_fdb_flow() is called while holding ESW devcom comp lock. This results in an AA deadlock. To fix this, introduce a new PEER flag that is set on flows created as peer flows (the duplicate flows on peer devices), and check it in mlx5e_tc_del_flow() before acquiring ESW devcom lock. Lockdep splat: ============================================ WARNING: possible recursive locking detected ============================================ Possible unsafe locking scenario: CPU0 ---- lock(&comp->lock_key#2); lock(&comp->lock_key#2); *** DEADLOCK *** Call Trace: <TASK> dump_stack_lvl+0x69/0xa0 print_deadlock_bug.cold+0xbd/0xca __lock_acquire+0x1671/0x2ec0 lock_acquire+0x10e/0x2e0 down_read+0x95/0x430 mlx5_devcom_for_each_peer_begin+0x4e/0xe0 [mlx5_core] mlx5e_tc_del_flow+0x11d/0xa70 [mlx5_core] mlx5e_flow_put+0x99/0x100

Description from the National Vulnerability Database, published by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

What it means for a small business

Linux is on the computers, phones or browsers your team uses every day. Turn on automatic updates and restart: most of these fixes only take effect after a restart.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.17%, higher than 6% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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