{"id":"CVE-2026-31680","revision":"4da3c4a51f064d5994cbfb8cb35a8377","records":[{"revision":"4da3c4a51f064d5994cbfb8cb35a8377","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-31680","aliases":[],"title":"net: ipv6: flowlabel: defer exclusive option free until RCU teardown","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: flowlabel: defer exclusive option free until RCU teardown\n\n`ip6fl_seq_show()` walks the global flowlabel hash under the seq-file\nRCU read-side lock and prints `fl->opt->opt_nflen` when an option block\nis present.\n\nExclusive flowlabels currently free `fl->opt` as soon as `fl->users`\ndrops to zero in `fl_release()`. However, the surrounding\n`struct ip6_flowlabel` remains visible in the global hash table until\nlater garbage collection removes it and `fl_free_rcu()` finally tears it\ndown.\n\nA concurrent `/proc/net/ip6_flowlabel` reader can therefore race that\nearly `kfree()` and dereference freed option state, triggering a crash\nin `ip6fl_seq_show()`.\n\nFix this by keeping `fl->opt` alive until `fl_free_rcu()`. That matches\nthe lifetime already required for the enclosing flowlabel while readers\ncan still reach it under RCU.","state":0,"publishedAt":"2026-04-25T08:46:56.807+00:00","modifiedAt":"2026-10-19T18:56:04.513+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_flowlabel.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"d3aedd5ebd4b0b925b0bcda548066803e1318499\",\n                            \"lessThan\": \"4b6798024f7b2d535f3db1002c760143cdbd1bd3\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d3aedd5ebd4b0b925b0bcda548066803e1318499\",\n                            \"lessThan\": \"3c54b66c83fb8fcbde8e6a7bf90b65856e39f827\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d3aedd5ebd4b0b925b0bcda548066803e1318499\",\n                            \"lessThan\": \"5a6b15f861b7c1304949e3350d23490a5fe429fd\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d3aedd5ebd4b0b925b0bcda548066803e1318499\",\n                            \"lessThan\": \"6c7fbdb8ffde6413640de7cfbd7c976c353e89f8\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d3aedd5ebd4b0b925b0bcda548066803e1318499\",\n                            \"lessThan\": \"8027964931785cb73d520ac70a342a3dc16c249b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d3aedd5ebd4b0b925b0bcda548066803e1318499\",\n                            \"lessThan\": \"414726b69921fe6355ae453f5b35e68dd078342a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d3aedd5ebd4b0b925b0bcda548066803e1318499\",\n                            \"lessThan\": \"572ce62778519a7d4d1c15f55dd2e45a474133c4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"d3aedd5ebd4b0b925b0bcda548066803e1318499\",\n                            \"lessThan\": \"9ca562bb8e66978b53028fa32b1a190708e6a091\",\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_flowlabel.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"3.9\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"3.9\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.10.253\",\n                            \"lessThanOrEqual\": \"5.10.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.203\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.168\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.134\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.81\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.22\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.19.12\",\n                            \"lessThanOrEqual\": \"6.19.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0\",\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/4b6798024f7b2d535f3db1002c760143cdbd1bd3","https://git.kernel.org/stable/c/3c54b66c83fb8fcbde8e6a7bf90b65856e39f827","https://git.kernel.org/stable/c/5a6b15f861b7c1304949e3350d23490a5fe429fd","https://git.kernel.org/stable/c/6c7fbdb8ffde6413640de7cfbd7c976c353e89f8","https://git.kernel.org/stable/c/8027964931785cb73d520ac70a342a3dc16c249b","https://git.kernel.org/stable/c/414726b69921fe6355ae453f5b35e68dd078342a","https://git.kernel.org/stable/c/572ce62778519a7d4d1c15f55dd2e45a474133c4","https://git.kernel.org/stable/c/9ca562bb8e66978b53028fa32b1a190708e6a091"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-31680","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-31680","identifiers":["CVE-2026-31680"]},"retained":false,"historicalAffected":[]}],"coverage":[]}