{"id":"CVE-2026-43501","revision":"847fc2ab695f4594ba8aee5aa16d6364","records":[{"revision":"847fc2ab695f4594ba8aee5aa16d6364","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-43501","aliases":[],"title":"ipv6: rpl: reserve mac_len headroom when recompressed SRH grows","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: rpl: reserve mac_len headroom when recompressed SRH grows\n\nipv6_rpl_srh_rcv() decompresses an RFC 6554 Source Routing Header, swaps\nthe next segment into ipv6_hdr->daddr, recompresses, then pulls the old\nheader and pushes the new one plus the IPv6 header back.  The\nrecompressed header can be larger than the received one when the swap\nreduces the common-prefix length the segments share with daddr (CmprI=0,\nCmprE>0, seg[0][0] != daddr[0] gives the maximum +8 bytes).\n\npskb_expand_head() was gated on segments_left == 0, so on earlier\nsegments the push consumed unchecked headroom.  Once skb_push() leaves\nfewer than skb->mac_len bytes in front of data,\nskb_mac_header_rebuild()'s call to:\n\n\tskb_set_mac_header(skb, -skb->mac_len);\n\nwill store (data - head) - mac_len into the u16 mac_header field, which\nwraps to ~65530, and the following memmove() writes mac_len bytes ~64KiB\npast skb->head.\n\nA single AF_INET6/SOCK_RAW/IPV6_HDRINCL packet over lo with a two\nsegment type-3 SRH (CmprI=0, CmprE=15) reaches headroom 8 after one\npass; KASAN reports a 14-byte OOB write in ipv6_rthdr_rcv.\n\nFix this by expanding the head whenever the remaining room is less than\nthe push size plus mac_len, and request that much extra so the rebuilt\nMAC header fits afterwards.","state":0,"publishedAt":"2026-05-21T12:17:49.885+00:00","modifiedAt":"2026-10-19T19:26:38.012+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/ipv6/exthdrs.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3\",\n                            \"lessThan\": \"bde199c72d319a4e207f88daabc888317504e2fb\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3\",\n                            \"lessThan\": \"be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3\",\n                            \"lessThan\": \"0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3\",\n                            \"lessThan\": \"8e8be63465a5e80394c70324603dfea1bfdad48f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3\",\n                            \"lessThan\": \"4babc2d9fda2df43823b85d08a0180b68f1b0854\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3\",\n                            \"lessThan\": \"c261d07a80576dc8ccf394ef8f074f8c67a06b37\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3\",\n                            \"lessThan\": \"7398ebefbfd4f8a31d4f665a4213302fa995494b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3\",\n                            \"lessThan\": \"9e6bf146b55999a095bb14f73a843942456d1adc\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/ipv6/exthdrs.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"5.7\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"5.7\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.10.258\",\n                            \"lessThanOrEqual\": \"5.10.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.209\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.175\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.140\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.86\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.27\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0.4\",\n                            \"lessThanOrEqual\": \"7.0.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/bde199c72d319a4e207f88daabc888317504e2fb","https://git.kernel.org/stable/c/be1fa0aa9b4fdd5a8b7a61ba520a690a68391e6e","https://git.kernel.org/stable/c/0a9e8053f1f8a8e1bfc1dd61ffe67be6c1180402","https://git.kernel.org/stable/c/8e8be63465a5e80394c70324603dfea1bfdad48f","https://git.kernel.org/stable/c/4babc2d9fda2df43823b85d08a0180b68f1b0854","https://git.kernel.org/stable/c/c261d07a80576dc8ccf394ef8f074f8c67a06b37","https://git.kernel.org/stable/c/7398ebefbfd4f8a31d4f665a4213302fa995494b","https://git.kernel.org/stable/c/9e6bf146b55999a095bb14f73a843942456d1adc"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43501","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-43501","identifiers":["CVE-2026-43501"]},"retained":false,"historicalAffected":[]}],"coverage":[]}