netfilter: flowtable: avoid num_encaps underflow on bridge VLAN untag
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 ].
CVE-2026-80634
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-80634
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "e990cef6516daa4e1e236433579e333f74fd38cb",
"lessThan": "1b52aeb40c9f04bf50eeb4ea09142139d163e239",
"versionType": "git"
},
{
"status": "affected",
"version": "e990cef6516daa4e1e236433579e333f74fd38cb",
"lessThan": "ee8440bb000fff4ef8acbfc99652851e9ca0a35b",
"versionType": "git"
},
{
"status": "affected",
"version": "e990cef6516daa4e1e236433579e333f74fd38cb",
"lessThan": "547ea9f567498e4accc89e7816264f15a1a0629f",
"versionType": "git"
},
{
"status": "affected",
"version": "e990cef6516daa4e1e236433579e333f74fd38cb",
"lessThan": "2f55fa28011c97d6495d5787808db10a8c2d690d",
"versionType": "git"
},
{
"status": "affected",
"version": "e990cef6516daa4e1e236433579e333f74fd38cb",
"lessThan": "e052f920773b73be49eb4d8702a9f85de7464363",
"versionType": "git"
}
],
"programFiles": [
"net/netfilter/nf_flow_table_path.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.13"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.13",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.114",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.57",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/netfilter/nf_flow_table_path.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-80634
Source reference:
/cveMetadata/cveId
Publisher severity
critical
Source reference: /containers/cna/metrics
- Event
- #46616 · Revision 1
- Added to Heist Feed
- Publisher date