CVE-2026-53211: netfilter: nft_meta_bridge: fix stale stack leak via IIFHWADDR register

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-25 · updated 2026-07-02
Weakness: CWE-401

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_meta_bridge: fix stale stack leak via IIFHWADDR register NFT_META_BRI_IIFHWADDR declares its destination register with len = ETH_ALEN (6 bytes), which the register-init tracking rounds up to two 32-bit registers (8 bytes). nft_meta_bridge_get_eval() then does memcpy(dest, br_dev->dev_addr, ETH_ALEN), writing only 6 bytes and leaving the upper 2 bytes of the second register as uninitialised nft_do_chain() stack. A downstream load of that register span leaks those stale bytes to userspace. Zero the second register before the memcpy so the full declared span is written.

Affected products

Linux kernel: from 6.18 before 6.18.36; from 6.19 before 7.0.13; 7.1-rc1, 7.1-rc2, 7.1-rc3, 7.1-rc4, 7.1-rc5, 7.1-rc6 (+1) — fixed in 6.18.36, 7.0.13

How to fix

Upgrade to a fixed version: Linux kernel 6.18.36, 7.0.13. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-53211 or the next vulnerability affects your stack