cve 2026 31422

About this tag
CVE-2026-31422 is a Linux kernel vulnerability in the net/sched/cls_flow module where flow_change() can dereference an unset b->q pointer when the filter is attached to a shared block, leading to a NULL pointer dereference and kernel crash. The flaw is triggered via tc_new_tfilter() and rtnetlink_rcv_msg(), with the crash reproduced at cls_flow.c:508. The fix adds a check for tcf_block_shared() to prevent the dereference. This tag covers discussions about the vulnerability, its reproduction, and the targeted patch for shared blocks in the Linux networking stack.

  1. CVE-2026-31422: Linux cls_flow NULL Dereference Fix for Shared Blocks

    CVE-2026-31422 is a classic example of how a small assumption in the Linux networking stack can turn into a kernel crash. The flaw lives in net/sched/cls_flow, where flow_change() can dereference b->q to derive a default baseclass even when the filter is attached to a shared block that...
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