{"id":"CVE-2026-80978","revision":"853af0625aa34090b4b7afaae2f2c557","records":[{"revision":"853af0625aa34090b4b7afaae2f2c557","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-80978","aliases":[],"title":"net: cap advertised IP tunnel headroom","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: cap advertised IP tunnel headroom\n\nIP tunnel devices derive their advertised needed_headroom from lower\noutput devices. A stack of user-created devices can make the derived\nvalue larger than the 16-bit skb header offsets can represent. Once IP\noutput reserves it, skb head expansion can wrap those offsets.\n\nThe runtime transmit path already caps a growing needed_headroom at 512.\nApply the same cap when tunnel configuration publishes needed_headroom\nderived from a lower output device.\n\nCapping the advertised value is safe: IP tunnel transmit still expands\nthe skb when a packet needs more headroom. A nonsensical stacked\nconfiguration can therefore incur an extra reallocation, but it cannot\npublish an unbounded reservation to upper layers.","state":0,"publishedAt":"2026-09-11T19:42:39.496+00:00","modifiedAt":"2026-10-19T08:46:02.787+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                        \"include/net/ip_tunnels.h\",\n                        \"net/ipv4/ip_tunnel.c\",\n                        \"net/ipv6/ip6_gre.c\",\n                        \"net/ipv6/ip6_tunnel.c\",\n                        \"net/ipv6/sit.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"1a37e412a0225fcba5587f24c0dfc7636efc8b69\",\n                            \"lessThan\": \"fb889a619723032140f5d983a3a34d25a5a2bed4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a37e412a0225fcba5587f24c0dfc7636efc8b69\",\n                            \"lessThan\": \"b160422f8103574425e2834130e169d84c94fa1d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a37e412a0225fcba5587f24c0dfc7636efc8b69\",\n                            \"lessThan\": \"d36e75f5669140b66515ad3a176ca6337bd80a5e\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a37e412a0225fcba5587f24c0dfc7636efc8b69\",\n                            \"lessThan\": \"84783961cb8bdb36b4f41a02ce43aafc6d52b176\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a37e412a0225fcba5587f24c0dfc7636efc8b69\",\n                            \"lessThan\": \"bc4e05ae66c9797a0972ac44326e69c5305e0020\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a37e412a0225fcba5587f24c0dfc7636efc8b69\",\n                            \"lessThan\": \"af0ee8f04bea22cdb331fa3509e17f81b48938ad\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a37e412a0225fcba5587f24c0dfc7636efc8b69\",\n                            \"lessThan\": \"9144f2c53a04465a6878172b523f640313c5559e\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1a37e412a0225fcba5587f24c0dfc7636efc8b69\",\n                            \"lessThan\": \"6b222adeb9340306e2ff97127c76117abb9b3df8\",\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                        \"include/net/ip_tunnels.h\",\n                        \"net/ipv4/ip_tunnel.c\",\n                        \"net/ipv6/ip6_gre.c\",\n                        \"net/ipv6/ip6_tunnel.c\",\n                        \"net/ipv6/sit.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"3.11\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"3.11\",\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/fb889a619723032140f5d983a3a34d25a5a2bed4","https://git.kernel.org/stable/c/b160422f8103574425e2834130e169d84c94fa1d","https://git.kernel.org/stable/c/d36e75f5669140b66515ad3a176ca6337bd80a5e","https://git.kernel.org/stable/c/84783961cb8bdb36b4f41a02ce43aafc6d52b176","https://git.kernel.org/stable/c/bc4e05ae66c9797a0972ac44326e69c5305e0020","https://git.kernel.org/stable/c/af0ee8f04bea22cdb331fa3509e17f81b48938ad","https://git.kernel.org/stable/c/9144f2c53a04465a6878172b523f640313c5559e","https://git.kernel.org/stable/c/6b222adeb9340306e2ff97127c76117abb9b3df8"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-80978","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-80978","identifiers":["CVE-2026-80978"]},"retained":false,"historicalAffected":[]}],"coverage":[]}