CVE-2026-80634 (GCVE-0-2026-80634)
Vulnerability from cvelistv5
Published
2026-08-28 06:48
Modified
2026-10-30 12:30
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: avoid num_encaps underflow on bridge VLAN untag The DEV_PATH_BR_VLAN_UNTAG case post-decrements info->num_encaps inside WARN_ON_ONCE(). num_encaps is u8, so if it's already 0 the decrement still happens and wraps it to 255. The break only leaves the inner switch -- a later path entry can set info->indev back to a real device, and we end up returning with num_encaps == 255. nft_dev_forward_path() then walks info.encap[] (size 2) up to num_encaps, which means an OOB stack read and a bogus count copied into the route descriptor. Should only happen on a malformed bridge path stack, hence the WARN, but worth handling sanely. Move the decrement out of the WARN. [ While at this, remove the WARN_ON_ONCE since this can only happen with a buggy bridge path stack --pablo ].
References
Impacted products
Vendor Product Version
Linux Linux Version: e990cef6516daa4e1e236433579e333f74fd38cb
Version: e990cef6516daa4e1e236433579e333f74fd38cb
Version: e990cef6516daa4e1e236433579e333f74fd38cb
Version: e990cef6516daa4e1e236433579e333f74fd38cb
Version: e990cef6516daa4e1e236433579e333f74fd38cb
Version: e990cef6516daa4e1e236433579e333f74fd38cb
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