CVE-2026-64522: net/mlx5e: Fix eswitch mode block underflow on IPsec acquire SA

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-25 · updated 2026-10-19
Weakness: CWE-190

Description

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Fix eswitch mode block underflow on IPsec acquire SA mlx5e_xfrm_add_state() handles acquire-flow temporary SAs by allocating software state and skipping hardware offload setup. That path jumps to the common success label before taking the eswitch mode block. After tunnel-mode validation was moved earlier, the common success label unconditionally calls mlx5_eswitch_unblock_mode(). For acquire SAs, this decrements esw->offloads.num_block_mode without a matching increment. Return directly after installing the acquire SA offload handle, so only the paths that successfully called mlx5_eswitch_block_mode() call the matching unblock.

Affected products

Linux kernel: from 6.17.4 before 6.18; 6.18 — fixed in 6.18, 7.1

How to fix

Upgrade to a fixed version: Linux kernel 6.18, 7.1. Check the vendor advisory for mitigations.

References

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