Answer in brief
CVE-2026-31422 records a Medium severity (CVSS 5.5) vulnerability in net/sched: cls_flow: fix NULL pointer dereference on shared blocks. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2026-31422 records a Medium severity (CVSS 5.5) vulnerability in net/sched: cls_flow: fix NULL pointer dereference on shared blocks. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=1abf272022cf1d18469405f47b4ec49c6a3125db <57f94ac7e953eece5ed4819605a18f3cdfc63dcc || >=1abf272022cf1d18469405f47b4ec49c6a3125db <942813276edeb1741fa5b0a73471beb4e495fa08 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <cc707a4fd4c3b6ab2722e06bc359aa010e13d408 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <4a09f72007201c9f667dc47f64517ec23eea65e5 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957e || >=1abf272022cf1d18469405f47b4ec49c6a3125db <a208c3e1232997e9317887294c20008dfcb75449 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <415ea0c973c754b9f375225807810eb9045f4293 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <1a280dd4bd1d616a01d6ffe0de284c907b555504 | 57f94ac7e953eece5ed4819605a18f3cdfc63dcc, 942813276edeb1741fa5b0a73471beb4e495fa08, cc707a4fd4c3b6ab2722e06bc359aa010e13d408, 4a09f72007201c9f667dc47f64517ec23eea65e5, 9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957e, a208c3e1232997e9317887294c20008dfcb75449, 415ea0c973c754b9f375225807810eb9045f4293, 1a280dd4bd1d616a01d6ffe0de284c907b555504 |
| Linux/Linuxgeneric | 4.15 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
Published upstream
Apr 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 14, 2026
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) [...] =======================================================================
Quoted source text, attributed separately from HOL analysis.
CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=1abf272022cf1d18469405f47b4ec49c6a3125db <57f94ac7e953eece5ed4819605a18f3cdfc63dcc || >=1abf272022cf1d18469405f47b4ec49c6a3125db <942813276edeb1741fa5b0a73471beb4e495fa08 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <cc707a4fd4c3b6ab2722e06bc359aa010e13d408 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <4a09f72007201c9f667dc47f64517ec23eea65e5 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957e || >=1abf272022cf1d18469405f47b4ec49c6a3125db <a208c3e1232997e9317887294c20008dfcb75449 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <415ea0c973c754b9f375225807810eb9045f4293 || >=1abf272022cf1d18469405f47b4ec49c6a3125db <1a280dd4bd1d616a01d6ffe0de284c907b555504 | 57f94ac7e953eece5ed4819605a18f3cdfc63dcc, 942813276edeb1741fa5b0a73471beb4e495fa08, cc707a4fd4c3b6ab2722e06bc359aa010e13d408, 4a09f72007201c9f667dc47f64517ec23eea65e5, 9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957e, a208c3e1232997e9317887294c20008dfcb75449, 415ea0c973c754b9f375225807810eb9045f4293, 1a280dd4bd1d616a01d6ffe0de284c907b555504 |
| Linux/Linuxgeneric | 4.15 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
Published upstream
Apr 13, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 14, 2026
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) [...] =======================================================================
Quoted source text, attributed separately from HOL analysis.