Out-of-bounds stack read via encapsulation-count underflow
Published Aug 28, 2026 · Updated Aug 28, 2026
An out-of-bounds read in Linux kernel netfilter flowtables allows attackers to copy stack data via a malformed bridge path. In nft_dev_path_info, DEV_PATH_BR_VLAN_UNTAG post-decrements the u8 num_encaps counter inside WARN_ON_ONCE, wrapping zero to 255; nft_dev_forward_path then walks the two-entry info.encap array using that value. A malformed bridge path stack with zero encapsulations is required; the disclosed consequence is a stack read and corrupted route metadata.
Summary
What happened
An out-of-bounds read in Linux kernel netfilter flowtables allows attackers to copy stack data via a malformed bridge path. In nft_dev_path_info, DEV_PATH_BR_VLAN_UNTAG post-decrements the u8 num_encaps counter inside WARN_ON_ONCE, wrapping zero to 255; nft_dev_forward_path then walks the two-entry info.encap array using that value. A malformed bridge path stack with zero encapsulations is required; the disclosed consequence is a stack read and corrupted route metadata.
The record
- CVE
- CVE-2026-80634
- Published
- Aug 28, 2026
- Updated
- Aug 28, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Aug 28, 2026CVE publishedPublication date reported by the CVE source.
- Aug 28, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=5.13
- Affected versionversion=e990cef6516daa4e1e236433579e333f74fd38cb <2f55fa28011c97d6495d5787808db10a8c2d690d
- Affected versionversion=e990cef6516daa4e1e236433579e333f74fd38cb <e052f920773b73be49eb4d8702a9f85de7464363
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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Your stack
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