Answer in brief
CVE-2026-43027 records a High severity (CVSS 7.8) vulnerability in netfilter: nf_conntrack_helper: pass helper to expect cleanup. 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-2026-43027 records a High severity (CVSS 7.8) vulnerability in netfilter: nf_conntrack_helper: pass helper to expect cleanup. 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 7.8. 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 | >=ac7b848390036dadd4351899d2a23748075916bd <5cf28d5c8dcbbe8af6d3b145babe491906d7bad1 || >=ac7b848390036dadd4351899d2a23748075916bd <504ba4168466c91210c45acdc332479cfd5f2da6 || >=ac7b848390036dadd4351899d2a23748075916bd <dc1739eff48e34cc71d4e2f03715493fbcebd8af || >=ac7b848390036dadd4351899d2a23748075916bd <2cf2737c85a2ba2b52024dafe68ffad2676f97be || >=ac7b848390036dadd4351899d2a23748075916bd <2c16e4d64dd91227742dfe196a3e7b0568bef65a || >=ac7b848390036dadd4351899d2a23748075916bd <620f3d14c1ef51d425060a3056ad8dbae8f998a3 || >=ac7b848390036dadd4351899d2a23748075916bd <90bd7e8501349db3006d21fbc09df9ffcb172965 || >=ac7b848390036dadd4351899d2a23748075916bd <a242a9ae58aa46ff7dae51ce64150a93957abe65 | 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1, 504ba4168466c91210c45acdc332479cfd5f2da6, dc1739eff48e34cc71d4e2f03715493fbcebd8af, 2cf2737c85a2ba2b52024dafe68ffad2676f97be, 2c16e4d64dd91227742dfe196a3e7b0568bef65a, 620f3d14c1ef51d425060a3056ad8dbae8f998a3, 90bd7e8501349db3006d21fbc09df9ffcb172965, a242a9ae58aa46ff7dae51ce64150a93957abe65 |
| Linux/Linuxgeneric | 4.14 | 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
May 1, 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: netfilter: nf_conntrack_helper: pass helper to expect cleanup nf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy() to remove expectations belonging to the helper being unregistered. However, it passes NULL instead of the helper pointer as the data argument, so expect_iter_me() never matches any expectation and all of them survive the cleanup. After unregister returns, nfnl_cthelper_del() frees the helper object immediately. Subsequent expectation dumps or packet-driven init_conntrack() calls then dereference the freed exp->helper, causing a use-after-free. Pass the actual helper pointer so expectations referencing it are properly destroyed before the helper object is freed. BUG: KASAN: slab-use-after-free in string+0x38f/0x430 Read of size 1 at addr ffff888003b14d20 by task poc/103 Call Trace: string+0x38f/0x430 vsnprintf+0x3cc/0x1170 seq_printf+0x17a/0x240 exp_seq_show+0x2e5/0x560 seq_read_iter+0x419/0x1280 proc_reg_read+0x1ac/0x270 vfs_read+0x179/0x930 ksys_read+0xef/0x1c0 Freed by task 103: The buggy address is located 32 bytes inside of freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)
Quoted source text, attributed separately from HOL analysis.
CVSS is 7.8. 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 | >=ac7b848390036dadd4351899d2a23748075916bd <5cf28d5c8dcbbe8af6d3b145babe491906d7bad1 || >=ac7b848390036dadd4351899d2a23748075916bd <504ba4168466c91210c45acdc332479cfd5f2da6 || >=ac7b848390036dadd4351899d2a23748075916bd <dc1739eff48e34cc71d4e2f03715493fbcebd8af || >=ac7b848390036dadd4351899d2a23748075916bd <2cf2737c85a2ba2b52024dafe68ffad2676f97be || >=ac7b848390036dadd4351899d2a23748075916bd <2c16e4d64dd91227742dfe196a3e7b0568bef65a || >=ac7b848390036dadd4351899d2a23748075916bd <620f3d14c1ef51d425060a3056ad8dbae8f998a3 || >=ac7b848390036dadd4351899d2a23748075916bd <90bd7e8501349db3006d21fbc09df9ffcb172965 || >=ac7b848390036dadd4351899d2a23748075916bd <a242a9ae58aa46ff7dae51ce64150a93957abe65 | 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1, 504ba4168466c91210c45acdc332479cfd5f2da6, dc1739eff48e34cc71d4e2f03715493fbcebd8af, 2cf2737c85a2ba2b52024dafe68ffad2676f97be, 2c16e4d64dd91227742dfe196a3e7b0568bef65a, 620f3d14c1ef51d425060a3056ad8dbae8f998a3, 90bd7e8501349db3006d21fbc09df9ffcb172965, a242a9ae58aa46ff7dae51ce64150a93957abe65 |
| Linux/Linuxgeneric | 4.14 | 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
May 1, 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: netfilter: nf_conntrack_helper: pass helper to expect cleanup nf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy() to remove expectations belonging to the helper being unregistered. However, it passes NULL instead of the helper pointer as the data argument, so expect_iter_me() never matches any expectation and all of them survive the cleanup. After unregister returns, nfnl_cthelper_del() frees the helper object immediately. Subsequent expectation dumps or packet-driven init_conntrack() calls then dereference the freed exp->helper, causing a use-after-free. Pass the actual helper pointer so expectations referencing it are properly destroyed before the helper object is freed. BUG: KASAN: slab-use-after-free in string+0x38f/0x430 Read of size 1 at addr ffff888003b14d20 by task poc/103 Call Trace: string+0x38f/0x430 vsnprintf+0x3cc/0x1170 seq_printf+0x17a/0x240 exp_seq_show+0x2e5/0x560 seq_read_iter+0x419/0x1280 proc_reg_read+0x1ac/0x270 vfs_read+0x179/0x930 ksys_read+0xef/0x1c0 Freed by task 103: The buggy address is located 32 bytes inside of freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)
Quoted source text, attributed separately from HOL analysis.