{"id":"CVE-2026-46086","summary":"net: bridge: use a stable FDB dst snapshot in RCU readers","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: use a stable FDB dst snapshot in RCU readers\n\nLocal FDB entries can be rewritten in place by `fdb_delete_local()`, which\nupdates `f-\u003edst` to another port or to `NULL` while keeping the entry\nalive. Several bridge RCU readers inspect `f-\u003edst`, including\n`br_fdb_fillbuf()` through the `brforward_read()` sysfs path.\n\nThese readers currently load `f-\u003edst` multiple times and can therefore\nobserve inconsistent values across the check and later dereference.\nIn `br_fdb_fillbuf()`, this means a concurrent local-FDB update can change\n`f-\u003edst` after the NULL check and before the `port_no` dereference,\nleading to a NULL-ptr-deref.\n\nFix this by taking a single `READ_ONCE()` snapshot of `f-\u003edst` in each\naffected RCU reader and using that snapshot for the rest of the access\nsequence. Also publish the in-place `f-\u003edst` updates in `fdb_delete_local()`\nwith `WRITE_ONCE()` so the readers and writer use matching access patterns.","modified":"2026-06-26T11:57:11.934842675Z","published":"2026-05-27T12:58:28.137Z","related":["openSUSE-SU-2026:10954-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46086.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0b9e4bbfb7c949151e3acd44ed4aa33614d2e110"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1406c4e0ed1eaf8a29801ab1163d00fb7ee4359a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5424e678f9b304e148cf5dcc047cffc7a56a3bb5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/81af4137a30c4c2dc694dea8cacb180bd66000ef"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9a2d9d4e657b23dc21f24cf139e3aeff0b61341f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a6ae4511c07b91f597e461406c6330f0d4ff810e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c502fa9f094cb03d1d1685c71e2105ab359bc2b8"},{"type":"WEB","url":"https://git.kernel.org/stable/c/df4601653201de21b487c3e7fffd464790cab808"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46086.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-46086"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"960b589f86c74ce582922fcb996103271081f4de"},{"fixed":"c502fa9f094cb03d1d1685c71e2105ab359bc2b8"},{"fixed":"a6ae4511c07b91f597e461406c6330f0d4ff810e"},{"fixed":"1406c4e0ed1eaf8a29801ab1163d00fb7ee4359a"},{"fixed":"0b9e4bbfb7c949151e3acd44ed4aa33614d2e110"},{"fixed":"81af4137a30c4c2dc694dea8cacb180bd66000ef"},{"fixed":"5424e678f9b304e148cf5dcc047cffc7a56a3bb5"},{"fixed":"9a2d9d4e657b23dc21f24cf139e3aeff0b61341f"},{"fixed":"df4601653201de21b487c3e7fffd464790cab808"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-46086.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.14.0"},{"fixed":"5.10.259"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.210"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.176"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.140"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.86"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.27"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-46086.json"}}],"schema_version":"1.7.5"}