net: bridge: fix use-after-free due to MST port state bypass
In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix use-after-free due to MST port state bypass syzbot reported[1] a use-after-free when deleting an expired fdb. It is due to a race condition between learning still happening and a port being deleted, after all its fdbs have been flushed. The port's state has been toggled to disabled so no learning should happen at that time, but if we have MST enabled, it will bypass the port's state, that together with VLAN filtering disabled can lead to fdb learning at a time when it shouldn't happen while the port is being deleted. VLAN filtering must be disabled because we flush the port VLANs when it's being deleted which will stop learning. This fix adds a check for the port's vlan group which is initialized to NULL when the port is getting deleted, that avoids the port state bypass. When MST is enabled there would be a minimal new overhead in the fast-path because the port's vlan group pointer is cache-hot. [1] https://syzkaller.appspot.com/bug?extid=dd280197f0f7ab3917be
CVE-2025-40297
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-2025-40297
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": "ec7328b59176227216c461601c6bd0e922232a9b",
"lessThan": "e19085b2a86addccff33ab8536fc67ebd9d52198",
"versionType": "git"
},
{
"status": "affected",
"version": "ec7328b59176227216c461601c6bd0e922232a9b",
"lessThan": "3b60ce334c1ce8b3fad7e02dcd5ed9f6646477c8",
"versionType": "git"
},
{
"status": "affected",
"version": "ec7328b59176227216c461601c6bd0e922232a9b",
"lessThan": "bf3843183bc3158e5821b46f330c438ae9bd6ddb",
"versionType": "git"
},
{
"status": "affected",
"version": "ec7328b59176227216c461601c6bd0e922232a9b",
"lessThan": "991fbe1680cd41a5f97c92cd3a3496315df36e4b",
"versionType": "git"
},
{
"status": "affected",
"version": "ec7328b59176227216c461601c6bd0e922232a9b",
"lessThan": "8dca36978aa80bab9d4da130c211db75c9e00048",
"versionType": "git"
}
],
"programFiles": [
"net/bridge/br_forward.c",
"net/bridge/br_input.c",
"net/bridge/br_private.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.18"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.18",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.159",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.117",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.58",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.17.8",
"versionType": "semver",
"lessThanOrEqual": "6.17.*"
},
{
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/bridge/br_forward.c",
"net/bridge/br_input.c",
"net/bridge/br_private.h"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2025-40297
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #30708 · Revision 1
- Added to Heist Feed
- Publisher date