CVE-2026-64522 net/mlx5e: Fix eswitch mode block underflow on IPsec acquire SA
A logic error in the Linux kernel's mlx5e driver causes an integer underflow in eswitch mode blocks during IPsec SA acquisition, potentially leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-64522?
CVE-2026-64522 is a high-severity vulnerability in Linux, published on 25 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-190
Which versions are affected by CVE-2026-64522?
How do I fix CVE-2026-64522?
Apply the vendor's patch.
Is CVE-2026-64522 being exploited?
There is no known exploitation of CVE-2026-64522 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64522, DEBIAN-CVE-2026-64522, GHSA-x5f7-rh4c-gxvr, ROOT-OS-UBUNTU-2204-CVE-2026-64522, UBUNTU-CVE-2026-64522.