CVE-2026-31422
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_flow: fix NULL pointer dereference on shared blocks flow_change() calls tcf_block_q() and dereferences q->handle to derive a default baseclass.
Does this matter?
Lower severity and a low EPSS score (0.12%). Track it; it rarely justifies an emergency change on its own.
Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_flow: fix NULL pointer dereference on shared blocks flow_change() calls tcf_block_q() and dereferences q->handle to derive a default baseclass. Shared blocks leave block->q NULL, causing a NULL deref when a flow filter without a fully qualified baseclass is created on a shared block. Check tcf_block_shared() before accessing block->q and return -EINVAL for shared blocks. This avoids the null-deref shown below: ======================================================================= KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f] RIP: 0010:flow_change (net/sched/cls_flow.c:508) Call Trace: tc_new_tfilter (net/sched/cls_api.c:2432) rtnetlink_rcv_msg (net/core/rtnetlink.c:6980) [...] =======================================================================
- CVSS 3.1
- 5.5 MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.12% probability · 2th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-476
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/1a280dd4bd1d616a01d6ffe0de284c907b555504Patch
- https://git.kernel.org/stable/c/415ea0c973c754b9f375225807810eb9045f4293Patch
- https://git.kernel.org/stable/c/4a09f72007201c9f667dc47f64517ec23eea65e5Patch
- https://git.kernel.org/stable/c/57f94ac7e953eece5ed4819605a18f3cdfc63dccPatch
- https://git.kernel.org/stable/c/942813276edeb1741fa5b0a73471beb4e495fa08Patch
- https://git.kernel.org/stable/c/9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957ePatch
- https://git.kernel.org/stable/c/a208c3e1232997e9317887294c20008dfcb75449Patch
- https://git.kernel.org/stable/c/cc707a4fd4c3b6ab2722e06bc359aa010e13d408Patch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.