CVE-2023-53516: macvlan: add forgotten nla_policy for IFLA_MACVLAN_BC_CUTOFF

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-01 · updated 2026-06-17
Weakness: CWE-787

Description

In the Linux kernel, the following vulnerability has been resolved: macvlan: add forgotten nla_policy for IFLA_MACVLAN_BC_CUTOFF The previous commit 954d1fa1ac93 ("macvlan: Add netlink attribute for broadcast cutoff") added one additional attribute named IFLA_MACVLAN_BC_CUTOFF to allow broadcast cutfoff. However, it forgot to describe the nla_policy at macvlan_policy (drivers/net/macvlan.c). Hence, this suppose NLA_S32 (4 bytes) integer can be faked as empty (0 bytes) by a malicious user, which could leads to OOB in heap just like CVE-2023-3773. To fix it, this commit just completes the nla_policy description for IFLA_MACVLAN_BC_CUTOFF. This enforces the length check and avoids the potential OOB read.

Affected products

Linux kernel: from 6.4 before 6.4.8; 6.5-rc1, 6.5-rc2, 6.5-rc3 — fixed in 6.4.8

How to fix

Upgrade to a fixed version: Linux kernel 6.4.8. Check the vendor advisory for mitigations.

References

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