{"id":"CVE-2026-31422","state":"PUBLISHED","title":"net/sched: cls_flow: fix NULL pointer dereference on shared blocks","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_flow: fix NULL pointer dereference on shared blocks\n\nflow_change() calls tcf_block_q() and dereferences q->handle to derive\na default baseclass.  Shared blocks leave block->q NULL, causing a NULL\nderef when a flow filter without a fully qualified baseclass is created\non a shared block.\n\nCheck tcf_block_shared() before accessing block->q and return -EINVAL\nfor shared blocks.  This avoids the null-deref shown below:\n\n=======================================================================\nKASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]\nRIP: 0010:flow_change (net/sched/cls_flow.c:508)\nCall Trace:\n tc_new_tfilter (net/sched/cls_api.c:2432)\n rtnetlink_rcv_msg (net/core/rtnetlink.c:6980)\n [...]\n=======================================================================","publishedAt":"2026-04-13T13:40:25.911Z","updatedAt":"2026-10-15T01:16:02.769Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","status":"affected","lessThan":"57f94ac7e953eece5ed4819605a18f3cdfc63dcc","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","status":"affected","lessThan":"942813276edeb1741fa5b0a73471beb4e495fa08","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","status":"affected","lessThan":"cc707a4fd4c3b6ab2722e06bc359aa010e13d408","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","status":"affected","lessThan":"4a09f72007201c9f667dc47f64517ec23eea65e5","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","status":"affected","lessThan":"9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957e","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","status":"affected","lessThan":"a208c3e1232997e9317887294c20008dfcb75449","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","status":"affected","lessThan":"415ea0c973c754b9f375225807810eb9045f4293","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","status":"affected","lessThan":"1a280dd4bd1d616a01d6ffe0de284c907b555504","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/cls_flow.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.15","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.168","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.134","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.81","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.22","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.12","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/cls_flow.c"]}],"references":["https://git.kernel.org/stable/c/57f94ac7e953eece5ed4819605a18f3cdfc63dcc","https://git.kernel.org/stable/c/942813276edeb1741fa5b0a73471beb4e495fa08","https://git.kernel.org/stable/c/cc707a4fd4c3b6ab2722e06bc359aa010e13d408","https://git.kernel.org/stable/c/4a09f72007201c9f667dc47f64517ec23eea65e5","https://git.kernel.org/stable/c/9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957e","https://git.kernel.org/stable/c/a208c3e1232997e9317887294c20008dfcb75449","https://git.kernel.org/stable/c/415ea0c973c754b9f375225807810eb9045f4293","https://git.kernel.org/stable/c/1a280dd4bd1d616a01d6ffe0de284c907b555504","https://cert-portal.siemens.com/productcert/html/ssa-082556.html","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31422.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31422","state":"PUBLISHED","datePublished":"2026-04-13T13:40:25.911Z","dateUpdated":"2026-10-15T01:16:02.769Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.088Z"},"containers":{"cna":{"title":"net/sched: cls_flow: fix NULL pointer dereference on shared blocks","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_flow: fix NULL pointer dereference on shared blocks\n\nflow_change() calls tcf_block_q() and dereferences q->handle to derive\na default baseclass.  Shared blocks leave block->q NULL, causing a NULL\nderef when a flow filter without a fully qualified baseclass is created\non a shared block.\n\nCheck tcf_block_shared() before accessing block->q and return -EINVAL\nfor shared blocks.  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