{"id":"CVE-2026-31422","title":"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","summary":"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 …","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-476"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 4.15, < 5.10.253","linux_kernel >= 5.11, < 5.15.203","linux_kernel >= 5.16, < 6.1.168","linux_kernel >= 6.2, < 6.6.134","linux_kernel >= 6.7, < 6.12.81","linux_kernel >= 6.13, < 6.18.22","linux_kernel >= 6.19, < 6.19.12","linux_kernel = 7.0"],"patched":["linux_kernel 6.19.12"],"published":"2026-04-13","updated":"2026-10-15","sourceUpdated":"2026-10-15T02:19:04.020","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-31422","references":[{"url":"https://git.kernel.org/stable/c/1a280dd4bd1d616a01d6ffe0de284c907b555504","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/415ea0c973c754b9f375225807810eb9045f4293","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/4a09f72007201c9f667dc47f64517ec23eea65e5","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/57f94ac7e953eece5ed4819605a18f3cdfc63dcc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/942813276edeb1741fa5b0a73471beb4e495fa08","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a208c3e1232997e9317887294c20008dfcb75449","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cc707a4fd4c3b6ab2722e06bc359aa010e13d408","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-082556.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-457936.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00122,"epssPercentile":0.01989,"ingestedAt":"2026-09-08T15:33:26.991Z","slug":"CVE-2026-31422","body":"## Overview\n\nIn 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=======================================================================\n\n## Affected\n\n- `linux_kernel >= 4.15, < 5.10.253`\n- `linux_kernel >= 5.11, < 5.15.203`\n- `linux_kernel >= 5.16, < 6.1.168`\n- `linux_kernel >= 6.2, < 6.6.134`\n- `linux_kernel >= 6.7, < 6.12.81`\n- `linux_kernel >= 6.13, < 6.18.22`\n- `linux_kernel >= 6.19, < 6.19.12`\n- `linux_kernel = 7.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.19.12`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":221699,"id":"CVE-2026-31422","ts":1792035329526,"field":"cvss","old":null,"new":"5.5"},{"seq":221698,"id":"CVE-2026-31422","ts":1792035329526,"field":"severity","old":"none","new":"medium"}]}