{"id":"CVE-2026-74659","state":"PUBLISHED","title":"net: bridge: mrp: fix uninitialised bytes on the wire","description":"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->type = BR_MRP_SUB_TLV_HEADER_TEST_AUTO_MGR;\n\nso sub_tlv->length 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.","publishedAt":"2026-08-22T15:32:32.926Z","updatedAt":"2026-08-22T15:32:32.926Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"014c062d23c63ec77ef2cf17a0d9363c7441cc94","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"7ebc23ff03668042e0b0e4034bb1518d36198d9e","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"06d58b8d2f053ced82e01efaeb6e7c82891eed58","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"a5e385eeb2d6dbbbdebfa050e67c34734ae12693","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"5912cf1822fbe53ae275c147868740eb384a5d3e","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"e08665218040f8e312abe40f74543186f3c2c941","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"63488dba65ef91373ef616575b32eb0eb21459f4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_mrp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.14","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_mrp.c"]}],"references":["https://git.kernel.org/stable/c/014c062d23c63ec77ef2cf17a0d9363c7441cc94","https://git.kernel.org/stable/c/7ebc23ff03668042e0b0e4034bb1518d36198d9e","https://git.kernel.org/stable/c/06d58b8d2f053ced82e01efaeb6e7c82891eed58","https://git.kernel.org/stable/c/a5e385eeb2d6dbbbdebfa050e67c34734ae12693","https://git.kernel.org/stable/c/5912cf1822fbe53ae275c147868740eb384a5d3e","https://git.kernel.org/stable/c/e08665218040f8e312abe40f74543186f3c2c941","https://git.kernel.org/stable/c/63488dba65ef91373ef616575b32eb0eb21459f4"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74659.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74659","state":"PUBLISHED","datePublished":"2026-08-22T15:32:32.926Z","dateUpdated":"2026-08-22T15:32:32.926Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.924Z"},"containers":{"cna":{"title":"net: bridge: mrp: fix uninitialised bytes on the wire","descriptions":[{"lang":"en","value":"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->type = BR_MRP_SUB_TLV_HEADER_TEST_AUTO_MGR;\n\nso sub_tlv->length 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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"014c062d23c63ec77ef2cf17a0d9363c7441cc94","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"7ebc23ff03668042e0b0e4034bb1518d36198d9e","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"06d58b8d2f053ced82e01efaeb6e7c82891eed58","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"a5e385eeb2d6dbbbdebfa050e67c34734ae12693","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"5912cf1822fbe53ae275c147868740eb384a5d3e","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"e08665218040f8e312abe40f74543186f3c2c941","versionType":"git"},{"version":"f7458934b0791c39a001e4d902fc3bf697b439b5","status":"affected","lessThan":"63488dba65ef91373ef616575b32eb0eb21459f4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_mrp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.14","versionType":"semver"},{"version":"5.15.216","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.183","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/br_mrp.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/014c062d23c63ec77ef2cf17a0d9363c7441cc94"},{"url":"https://git.kernel.org/stable/c/7ebc23ff03668042e0b0e4034bb1518d36198d9e"},{"url":"https://git.kernel.org/stable/c/06d58b8d2f053ced82e01efaeb6e7c82891eed58"},{"url":"https://git.kernel.org/stable/c/a5e385eeb2d6dbbbdebfa050e67c34734ae12693"},{"url":"https://git.kernel.org/stable/c/5912cf1822fbe53ae275c147868740eb384a5d3e"},{"url":"https://git.kernel.org/stable/c/e08665218040f8e312abe40f74543186f3c2c941"},{"url":"https://git.kernel.org/stable/c/63488dba65ef91373ef616575b32eb0eb21459f4"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-22T15:32:32.926Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"5.15.216"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.6.152"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.12.104"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.18.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"7.1.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}