The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - net/sched: cls_fw: fix NULL pointer dereference on shared blocks The old-method path in fw_classify()     calls tcf_block_q() and dereferences q->handle. Shared blocks leave block->q NULL, causing a NULL deref     when an empty cls_fw filter is attached to a shared block and a packet with a nonzero major skb mark is     classified. Reject the configuration in fw_change() when the old method (no TCA_OPTIONS) is used on a     shared block, since fw_classify()'s old-method path needs block->q which is NULL for shared blocks. The     fixed null-ptr-deref calling stack: KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]     RIP: 0010:fw_classify (net/sched/cls_fw.c:81) Call Trace: tcf_classify (./include/net/tc_wrapper.h:197     net/sched/cls_api.c:1764 net/sched/cls_api.c:1860) tc_run (net/core/dev.c:4401) __dev_queue_xmit     (net/core/dev.c:4535 net/core/dev.c:4790) (CVE-2026-31421)

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Linux Distros Unpatched Vulnerability : CVE-2026-31421

medium Nessus Plugin ID 306182

Version 1.6