{"api_version":"1","generated_at":"2026-08-17T11:24:45+00:00","cve":"CVE-2026-74577","urls":{"html":"https://cve.report/CVE-2026-74577","api":"https://cve.report/api/cve/CVE-2026-74577.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74577","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74577"},"summary":{"title":"net: mpls: initialize rtm_tos in mpls_getroute()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: mpls: initialize rtm_tos in mpls_getroute()\n\nmpls_getroute() builds the RTM_NEWROUTE reply to an RTM_GETROUTE\nrequest by filling a struct rtmsg allocated from an skb whose data\narea is not zeroed (alloc_skb(NLMSG_GOODSIZE, ...)). It sets every\nfield of the header except rtm_tos:\n\n\tr = nlmsg_data(nlh);\n\tr->rtm_family\t = AF_MPLS;\n\tr->rtm_dst_len\t= 20;\n\tr->rtm_src_len\t= 0;\n\tr->rtm_table\t= RT_TABLE_MAIN;\n\tr->rtm_type\t= RTN_UNICAST;\n\tr->rtm_scope\t= RT_SCOPE_UNIVERSE;\n\tr->rtm_protocol = rt->rt_protocol;\n\tr->rtm_flags\t= 0;\n\nstruct rtmsg has no padding, so the one uninitialised byte rtm_tos\n(offset 3) is copied straight to user space on recvmsg(), leaking a\nbyte of uninitialised heap memory. This is in contrast to\nmpls_dump_route(), which fills the very same header and does set\nrtm_tos = 0.\n\nInitialize rtm_tos to 0, matching mpls_dump_route().\n\nReproduced with KMSAN by adding an MPLS route and issuing a\nnon-RTM_F_FIB_MATCH RTM_GETROUTE for its label:\n\n  BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x36c/0x33f0\n   _copy_to_iter+0x36c/0x33f0\n   __skb_datagram_iter+0x196/0x12c0\n   skb_copy_datagram_iter+0x5b/0x210\n   netlink_recvmsg+0x37b/0xef0\n   ...\n  Uninit was created at:\n   __alloc_skb+0x8ca/0x10e0\n   mpls_getroute+0x1280/0x3a40\n   rtnetlink_rcv_msg+0x1138/0x15a0\n   ...\n  Byte 19 of 64 is uninitialized\n\n(byte 19 = nlmsghdr(16) + rtmsg offset 3 = rtm_tos)","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 13:18:03","updated_at":"2026-08-17 06:19:56"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/295dd295e2137e10e9a5b1891d97e0f08de76f03","name":"https://git.kernel.org/stable/c/295dd295e2137e10e9a5b1891d97e0f08de76f03","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a5cdd2407dd890f741f59b8367e4c6c101cce154","name":"https://git.kernel.org/stable/c/a5cdd2407dd890f741f59b8367e4c6c101cce154","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2dc2fffc704a4365cae1aae078ba62223aaeff93","name":"https://git.kernel.org/stable/c/2dc2fffc704a4365cae1aae078ba62223aaeff93","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/95651461cf77cc6590fa08c87667717e5dcfa55d","name":"https://git.kernel.org/stable/c/95651461cf77cc6590fa08c87667717e5dcfa55d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1fea5ff0eb4aa7e951bb3d380248566c473aa377","name":"https://git.kernel.org/stable/c/1fea5ff0eb4aa7e951bb3d380248566c473aa377","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74577","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74577","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 397fc9e5cefee0c33b86811fbddb0decb7288c52 95651461cf77cc6590fa08c87667717e5dcfa55d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 397fc9e5cefee0c33b86811fbddb0decb7288c52 1fea5ff0eb4aa7e951bb3d380248566c473aa377 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 397fc9e5cefee0c33b86811fbddb0decb7288c52 a5cdd2407dd890f741f59b8367e4c6c101cce154 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 397fc9e5cefee0c33b86811fbddb0decb7288c52 2dc2fffc704a4365cae1aae078ba62223aaeff93 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 397fc9e5cefee0c33b86811fbddb0decb7288c52 295dd295e2137e10e9a5b1891d97e0f08de76f03 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.13","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.13 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.151 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.103 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.44 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.8 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"74577","cve":"CVE-2026-74577","epss":"0.001570000","percentile":"0.053420000","score_date":"2026-08-16","updated_at":"2026-08-17 00:01:04"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/mpls/af_mpls.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"95651461cf77cc6590fa08c87667717e5dcfa55d","status":"affected","version":"397fc9e5cefee0c33b86811fbddb0decb7288c52","versionType":"git"},{"lessThan":"1fea5ff0eb4aa7e951bb3d380248566c473aa377","status":"affected","version":"397fc9e5cefee0c33b86811fbddb0decb7288c52","versionType":"git"},{"lessThan":"a5cdd2407dd890f741f59b8367e4c6c101cce154","status":"affected","version":"397fc9e5cefee0c33b86811fbddb0decb7288c52","versionType":"git"},{"lessThan":"2dc2fffc704a4365cae1aae078ba62223aaeff93","status":"affected","version":"397fc9e5cefee0c33b86811fbddb0decb7288c52","versionType":"git"},{"lessThan":"295dd295e2137e10e9a5b1891d97e0f08de76f03","status":"affected","version":"397fc9e5cefee0c33b86811fbddb0decb7288c52","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/mpls/af_mpls.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.13"},{"lessThan":"4.13","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.151","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.103","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.44","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.8","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.151","versionStartIncluding":"4.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.103","versionStartIncluding":"4.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.44","versionStartIncluding":"4.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.8","versionStartIncluding":"4.13","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"4.13","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: mpls: initialize rtm_tos in mpls_getroute()\n\nmpls_getroute() builds the RTM_NEWROUTE reply to an RTM_GETROUTE\nrequest by filling a struct rtmsg allocated from an skb whose data\narea is not zeroed (alloc_skb(NLMSG_GOODSIZE, ...)). It sets every\nfield of the header except rtm_tos:\n\n\tr = nlmsg_data(nlh);\n\tr->rtm_family\t = AF_MPLS;\n\tr->rtm_dst_len\t= 20;\n\tr->rtm_src_len\t= 0;\n\tr->rtm_table\t= RT_TABLE_MAIN;\n\tr->rtm_type\t= RTN_UNICAST;\n\tr->rtm_scope\t= RT_SCOPE_UNIVERSE;\n\tr->rtm_protocol = rt->rt_protocol;\n\tr->rtm_flags\t= 0;\n\nstruct rtmsg has no padding, so the one uninitialised byte rtm_tos\n(offset 3) is copied straight to user space on recvmsg(), leaking a\nbyte of uninitialised heap memory. This is in contrast to\nmpls_dump_route(), which fills the very same header and does set\nrtm_tos = 0.\n\nInitialize rtm_tos to 0, matching mpls_dump_route().\n\nReproduced with KMSAN by adding an MPLS route and issuing a\nnon-RTM_F_FIB_MATCH RTM_GETROUTE for its label:\n\n  BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x36c/0x33f0\n   _copy_to_iter+0x36c/0x33f0\n   __skb_datagram_iter+0x196/0x12c0\n   skb_copy_datagram_iter+0x5b/0x210\n   netlink_recvmsg+0x37b/0xef0\n   ...\n  Uninit was created at:\n   __alloc_skb+0x8ca/0x10e0\n   mpls_getroute+0x1280/0x3a40\n   rtnetlink_rcv_msg+0x1138/0x15a0\n   ...\n  Byte 19 of 64 is uninitialized\n\n(byte 19 = nlmsghdr(16) + rtmsg offset 3 = rtm_tos)"}],"providerMetadata":{"dateUpdated":"2026-08-17T05:22:07.878Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/95651461cf77cc6590fa08c87667717e5dcfa55d"},{"url":"https://git.kernel.org/stable/c/1fea5ff0eb4aa7e951bb3d380248566c473aa377"},{"url":"https://git.kernel.org/stable/c/a5cdd2407dd890f741f59b8367e4c6c101cce154"},{"url":"https://git.kernel.org/stable/c/2dc2fffc704a4365cae1aae078ba62223aaeff93"},{"url":"https://git.kernel.org/stable/c/295dd295e2137e10e9a5b1891d97e0f08de76f03"}],"title":"net: mpls: initialize rtm_tos in mpls_getroute()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74577","datePublished":"2026-08-15T12:28:14.408Z","dateReserved":"2026-08-15T05:44:03.917Z","dateUpdated":"2026-08-17T05:22:07.878Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 13:18:03","lastModifiedDate":"2026-08-17 06:19:56","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74577","Ordinal":"1","Title":"net: mpls: initialize rtm_tos in mpls_getroute()","CVE":"CVE-2026-74577","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74577","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: mpls: initialize rtm_tos in mpls_getroute()\n\nmpls_getroute() builds the RTM_NEWROUTE reply to an RTM_GETROUTE\nrequest by filling a struct rtmsg allocated from an skb whose data\narea is not zeroed (alloc_skb(NLMSG_GOODSIZE, ...)). It sets every\nfield of the header except rtm_tos:\n\n\tr = nlmsg_data(nlh);\n\tr->rtm_family\t = AF_MPLS;\n\tr->rtm_dst_len\t= 20;\n\tr->rtm_src_len\t= 0;\n\tr->rtm_table\t= RT_TABLE_MAIN;\n\tr->rtm_type\t= RTN_UNICAST;\n\tr->rtm_scope\t= RT_SCOPE_UNIVERSE;\n\tr->rtm_protocol = rt->rt_protocol;\n\tr->rtm_flags\t= 0;\n\nstruct rtmsg has no padding, so the one uninitialised byte rtm_tos\n(offset 3) is copied straight to user space on recvmsg(), leaking a\nbyte of uninitialised heap memory. This is in contrast to\nmpls_dump_route(), which fills the very same header and does set\nrtm_tos = 0.\n\nInitialize rtm_tos to 0, matching mpls_dump_route().\n\nReproduced with KMSAN by adding an MPLS route and issuing a\nnon-RTM_F_FIB_MATCH RTM_GETROUTE for its label:\n\n  BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x36c/0x33f0\n   _copy_to_iter+0x36c/0x33f0\n   __skb_datagram_iter+0x196/0x12c0\n   skb_copy_datagram_iter+0x5b/0x210\n   netlink_recvmsg+0x37b/0xef0\n   ...\n  Uninit was created at:\n   __alloc_skb+0x8ca/0x10e0\n   mpls_getroute+0x1280/0x3a40\n   rtnetlink_rcv_msg+0x1138/0x15a0\n   ...\n  Byte 19 of 64 is uninitialized\n\n(byte 19 = nlmsghdr(16) + rtmsg offset 3 = rtm_tos)","Type":"Description","Title":"net: mpls: initialize rtm_tos in mpls_getroute()"}]}}}