net: bridge: use a stable FDB dst snapshot in RCU readers
In the Linux kernel, the following vulnerability has been resolved: net: bridge: use a stable FDB dst snapshot in RCU readers Local FDB entries can be rewritten in place by `fdb_delete_local()`, which updates `f->dst` to another port or to `NULL` while keeping the entry alive. Several bridge RCU readers inspect `f->dst`, including `br_fdb_fillbuf()` through the `brforward_read()` sysfs path. These readers currently load `f->dst` multiple times and can therefore observe inconsistent values across the check and later dereference. In `br_fdb_fillbuf()`, this means a concurrent local-FDB update can change `f->dst` after the NULL check and before the `port_no` dereference, leading to a NULL-ptr-deref. Fix this by taking a single `READ_ONCE()` snapshot of `f->dst` in each affected RCU reader and using that snapshot for the rest of the access sequence. Also publish the in-place `f->dst` updates in `fdb_delete_local()` with `WRITE_ONCE()` so the readers and writer use matching access patterns.
CVE-2026-46086
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-2026-46086
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": "960b589f86c74ce582922fcb996103271081f4de",
"lessThan": "c502fa9f094cb03d1d1685c71e2105ab359bc2b8",
"versionType": "git"
},
{
"status": "affected",
"version": "960b589f86c74ce582922fcb996103271081f4de",
"lessThan": "a6ae4511c07b91f597e461406c6330f0d4ff810e",
"versionType": "git"
},
{
"status": "affected",
"version": "960b589f86c74ce582922fcb996103271081f4de",
"lessThan": "1406c4e0ed1eaf8a29801ab1163d00fb7ee4359a",
"versionType": "git"
},
{
"status": "affected",
"version": "960b589f86c74ce582922fcb996103271081f4de",
"lessThan": "0b9e4bbfb7c949151e3acd44ed4aa33614d2e110",
"versionType": "git"
},
{
"status": "affected",
"version": "960b589f86c74ce582922fcb996103271081f4de",
"lessThan": "81af4137a30c4c2dc694dea8cacb180bd66000ef",
"versionType": "git"
},
{
"status": "affected",
"version": "960b589f86c74ce582922fcb996103271081f4de",
"lessThan": "5424e678f9b304e148cf5dcc047cffc7a56a3bb5",
"versionType": "git"
},
{
"status": "affected",
"version": "960b589f86c74ce582922fcb996103271081f4de",
"lessThan": "9a2d9d4e657b23dc21f24cf139e3aeff0b61341f",
"versionType": "git"
},
{
"status": "affected",
"version": "960b589f86c74ce582922fcb996103271081f4de",
"lessThan": "df4601653201de21b487c3e7fffd464790cab808",
"versionType": "git"
}
],
"programFiles": [
"net/bridge/br_arp_nd_proxy.c",
"net/bridge/br_fdb.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.14"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.14",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.259",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.210",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.176",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.140",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.86",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.27",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.4",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/bridge/br_arp_nd_proxy.c",
"net/bridge/br_fdb.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-46086
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #28386 · Revision 1
- Added to Heist Feed
- Publisher date