Bug 2492752 (CVE-2026-53211)

Summary: CVE-2026-53211 kernel: netfilter: nft_meta_bridge: fix stale stack leak via IIFHWADDR register
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's netfilter component, specifically in nft_meta_bridge. The NFT_META_BRI_IIFHWADDR register, intended for hardware address storage, is declared with a length of 6 bytes but is tracked as 8 bytes during initialization. When nft_meta_bridge_get_eval() writes to this register, only 6 bytes are written, leaving 2 bytes uninitialized. A subsequent operation that loads this register can leak these uninitialized stale stack bytes to userspace, leading to information disclosure.
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Description OSIDB Bzimport 2026-06-25 10:03:53 UTC 
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.
Comment 1 TEJ RATHI 2026-06-26 08:17:35 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062503-CVE-2026-53211-844b@gregkh/T