{"id":"CVE-2026-74659","summary":"net: bridge: mrp: fix uninitialised bytes on the wire","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: mrp: fix uninitialised bytes on the wire\n\nbr_mrp_alloc_test_skb() builds MRP test frames on an skb from\ndev_alloc_skb(), which does not clear the linear data area.  On the MRA\nring-role branch the sub-option TLV header is appended with\n\n\tsub_tlv = skb_put(skb, sizeof(*sub_tlv));\n\tsub_tlv-\u003etype = BR_MRP_SUB_TLV_HEADER_TEST_AUTO_MGR;\n\nso sub_tlv-\u003elength is never written, and the two trailing alignment bytes\nare appended with a bare skb_put() that does not clear them either.  The\nneighbouring oui and sub_opt regions are explicitly zeroed, so three\nuninitialised bytes are left in every MRA MRP_Test frame that goes out.\n\nPut the sub-option TLV header and the alignment padding in a single\nskb_put_zero(), which clears both.  The AUTO_MGR sub-TLV carries no\npayload, so the zeroed length field is already the value it should have.","modified":"2026-08-24T11:47:18.948274903Z","published":"2026-08-22T15:32:32.926Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74659.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/014c062d23c63ec77ef2cf17a0d9363c7441cc94"},{"type":"WEB","url":"https://git.kernel.org/stable/c/06d58b8d2f053ced82e01efaeb6e7c82891eed58"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5912cf1822fbe53ae275c147868740eb384a5d3e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/63488dba65ef91373ef616575b32eb0eb21459f4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7ebc23ff03668042e0b0e4034bb1518d36198d9e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a5e385eeb2d6dbbbdebfa050e67c34734ae12693"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e08665218040f8e312abe40f74543186f3c2c941"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74659.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74659"},{"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":"f7458934b0791c39a001e4d902fc3bf697b439b5"},{"fixed":"014c062d23c63ec77ef2cf17a0d9363c7441cc94"},{"fixed":"7ebc23ff03668042e0b0e4034bb1518d36198d9e"},{"fixed":"06d58b8d2f053ced82e01efaeb6e7c82891eed58"},{"fixed":"a5e385eeb2d6dbbbdebfa050e67c34734ae12693"},{"fixed":"5912cf1822fbe53ae275c147868740eb384a5d3e"},{"fixed":"e08665218040f8e312abe40f74543186f3c2c941"},{"fixed":"63488dba65ef91373ef616575b32eb0eb21459f4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74659.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.14.0"},{"fixed":"5.15.216"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.183"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.152"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.104"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.45"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74659.json"}}],"schema_version":"1.9.0"}