{"id":"CVE-2026-89563","revision":"88baec989c4b49f08e8c89055990f146","records":[{"revision":"88baec989c4b49f08e8c89055990f146","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-89563","aliases":[],"title":"ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()\n\nip6_tnl_xmit() may need to expand headroom before it can push the\nouter IPv6 and optional encap headers. It currently does that with\nskb_realloc_headroom(), copies skb->sk ownership, consumes the original\nskb, and then continues processing with the replacement skb kept only in\nits local variable.\n\nThat is safe only if the helper cannot fail afterwards. But this helper\nstill has post-reallocation error exits. collect_md tunnels reject\nnon-NONE encap after the replacement, and ip6_tnl_encap() can also fail\nlater. In those cases the helper returns an error to its callers while\nthe caller still only has the original skb pointer.\n\nBoth ip6_tnl_start_xmit() and the IPv6 GRE paths free the caller skb on\nerror, so they can end up freeing an skb that ip6_tnl_xmit() already\nconsumed.\n\nUse skb_cow_head() instead. It provides the required headroom and\nwritability without privately replacing the caller-owned skb, so later\nerror returns cannot leave callers with a stale pointer.\n\nThe Ethernet users, ip6gretap and ip6erspan, clear IFF_TX_SKB_SHARING\nand already call skb_cow_head() before entering ip6_tnl_xmit(). They do\nnot rely on the removed skb_shared() reallocation. This also makes the\nIPv6 tunnel path consistent with ip_tunnel_xmit().","state":0,"publishedAt":"2026-09-11T19:44:34.375+00:00","modifiedAt":"2026-10-19T08:48:56.784+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/ip6_tunnel.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"058214a4d1dfefed9f01a277fadd3590acb5f990\",\n                            \"lessThan\": \"6e8eff8ed13b14708bc39f170144eacde494aac6\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"058214a4d1dfefed9f01a277fadd3590acb5f990\",\n                            \"lessThan\": \"dc1a319a4815c074914e2812e0e9cd0164ca682b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"058214a4d1dfefed9f01a277fadd3590acb5f990\",\n                            \"lessThan\": \"629d5557e635cdbc109a14ed913ba5a540e3f79a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"058214a4d1dfefed9f01a277fadd3590acb5f990\",\n                            \"lessThan\": \"defa0adeff132cc90ed66915b9a104d9393e1e54\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"058214a4d1dfefed9f01a277fadd3590acb5f990\",\n                            \"lessThan\": \"37df5bc6b5ccad88c2faa0f5466f150178882b74\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"058214a4d1dfefed9f01a277fadd3590acb5f990\",\n                            \"lessThan\": \"b36dfd6e8cff00cea81c11cc0af88d1564763461\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"058214a4d1dfefed9f01a277fadd3590acb5f990\",\n                            \"lessThan\": \"8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"058214a4d1dfefed9f01a277fadd3590acb5f990\",\n                            \"lessThan\": \"87f21b59ddc618eff9670c174842964ad65fdade\",\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/ip6_tunnel.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4.7\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"4.7\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.10.270\",\n                            \"lessThanOrEqual\": \"5.10.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.221\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.188\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.157\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.109\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.50\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.4\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/6e8eff8ed13b14708bc39f170144eacde494aac6","https://git.kernel.org/stable/c/dc1a319a4815c074914e2812e0e9cd0164ca682b","https://git.kernel.org/stable/c/629d5557e635cdbc109a14ed913ba5a540e3f79a","https://git.kernel.org/stable/c/defa0adeff132cc90ed66915b9a104d9393e1e54","https://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74","https://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461","https://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52","https://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89563","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-89563","identifiers":["CVE-2026-89563"]},"retained":false,"historicalAffected":[]}],"coverage":[]}