Answer in brief
CVE-2026-31665 records a High severity (CVSS 7.8) vulnerability in netfilter: nft_ct: fix use-after-free in timeout object destroy. 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-2026-31665 records a High severity (CVSS 7.8) vulnerability in netfilter: nft_ct: fix use-after-free in timeout object destroy. 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 | >=7e0b2b57f01d183e1c84114f1f2287737358d748 <c458fc1c278a65ad5381083121d39a479973ebed || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <c581e5c8f2b59158f62efe61c1a3dc36189081ff || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <f16fe84879a5280f05ebbcea593a189ba0f3e79a || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <070abdf1b04325b21a20a2a0c39a2208af107275 || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77 || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <b42aca3660dc2627a29a38131597ca610dc451f9 || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <d0983b48c10d1509fd795c155f8b1e832e1369ff || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <f8dca15a1b190787bbd03285304b569631160eda | c458fc1c278a65ad5381083121d39a479973ebed, c581e5c8f2b59158f62efe61c1a3dc36189081ff, f16fe84879a5280f05ebbcea593a189ba0f3e79a, 070abdf1b04325b21a20a2a0c39a2208af107275, aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77, b42aca3660dc2627a29a38131597ca610dc451f9, d0983b48c10d1509fd795c155f8b1e832e1369ff, f8dca15a1b190787bbd03285304b569631160eda |
| Linux/Linuxgeneric | 4.19 | 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 24, 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: nft_ct: fix use-after-free in timeout object destroy nft_ct_timeout_obj_destroy() frees the timeout object with kfree() immediately after nf_ct_untimeout(), without waiting for an RCU grace period. Concurrent packet processing on other CPUs may still hold RCU-protected references to the timeout object obtained via rcu_dereference() in nf_ct_timeout_data(). Add an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer freeing until after an RCU grace period, matching the approach already used in nfnetlink_cttimeout.c. KASAN report: BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0 Read of size 4 at addr ffff8881035fe19c by task exploit/80 Call Trace: nf_conntrack_tcp_packet+0x1381/0x29d0 nf_conntrack_in+0x612/0x8b0 nf_hook_slow+0x70/0x100 __ip_local_out+0x1b2/0x210 tcp_sendmsg_locked+0x722/0x1580 __sys_sendto+0x2d8/0x320 Allocated by task 75: nft_ct_timeout_obj_init+0xf6/0x290 nft_obj_init+0x107/0x1b0 nf_tables_newobj+0x680/0x9c0 nfnetlink_rcv_batch+0xc29/0xe00 Freed by task 26: nft_obj_destroy+0x3f/0xa0 nf_tables_trans_destroy_work+0x51c/0x5c0 process_one_work+0x2c4/0x5a0
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 | >=7e0b2b57f01d183e1c84114f1f2287737358d748 <c458fc1c278a65ad5381083121d39a479973ebed || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <c581e5c8f2b59158f62efe61c1a3dc36189081ff || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <f16fe84879a5280f05ebbcea593a189ba0f3e79a || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <070abdf1b04325b21a20a2a0c39a2208af107275 || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77 || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <b42aca3660dc2627a29a38131597ca610dc451f9 || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <d0983b48c10d1509fd795c155f8b1e832e1369ff || >=7e0b2b57f01d183e1c84114f1f2287737358d748 <f8dca15a1b190787bbd03285304b569631160eda | c458fc1c278a65ad5381083121d39a479973ebed, c581e5c8f2b59158f62efe61c1a3dc36189081ff, f16fe84879a5280f05ebbcea593a189ba0f3e79a, 070abdf1b04325b21a20a2a0c39a2208af107275, aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77, b42aca3660dc2627a29a38131597ca610dc451f9, d0983b48c10d1509fd795c155f8b1e832e1369ff, f8dca15a1b190787bbd03285304b569631160eda |
| Linux/Linuxgeneric | 4.19 | 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 24, 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: nft_ct: fix use-after-free in timeout object destroy nft_ct_timeout_obj_destroy() frees the timeout object with kfree() immediately after nf_ct_untimeout(), without waiting for an RCU grace period. Concurrent packet processing on other CPUs may still hold RCU-protected references to the timeout object obtained via rcu_dereference() in nf_ct_timeout_data(). Add an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer freeing until after an RCU grace period, matching the approach already used in nfnetlink_cttimeout.c. KASAN report: BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0 Read of size 4 at addr ffff8881035fe19c by task exploit/80 Call Trace: nf_conntrack_tcp_packet+0x1381/0x29d0 nf_conntrack_in+0x612/0x8b0 nf_hook_slow+0x70/0x100 __ip_local_out+0x1b2/0x210 tcp_sendmsg_locked+0x722/0x1580 __sys_sendto+0x2d8/0x320 Allocated by task 75: nft_ct_timeout_obj_init+0xf6/0x290 nft_obj_init+0x107/0x1b0 nf_tables_newobj+0x680/0x9c0 nfnetlink_rcv_batch+0xc29/0xe00 Freed by task 26: nft_obj_destroy+0x3f/0xa0 nf_tables_trans_destroy_work+0x51c/0x5c0 process_one_work+0x2c4/0x5a0
Quoted source text, attributed separately from HOL analysis.