Answer in brief
CVE-2026-31504 records a High severity (CVSS 7.8) vulnerability in net: fix fanout UAF in packet_release() via NETDEV_UP race. 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-2026-31504 records a High severity (CVSS 7.8) vulnerability in net: fix fanout UAF in packet_release() via NETDEV_UP race. 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 | >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <ee642b1962caa9aa231c01abbd58bc453ae6b66e || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <42cfd7898eeed290c9fb73f732af1f7d6b0a703e || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <1b4c03f8892d955385c202009af7485364731bb9 || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <654386baef228c2992dbf604c819e4c7c35fc71b || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <75fe6db23705a1d55160081f7b37db9665b1880b || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6 || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <ceccbfc6de720ad633519a226715989cfb065af1 || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <42156f93d123436f2a27c468f18c966b7e5db796 | ee642b1962caa9aa231c01abbd58bc453ae6b66e, 42cfd7898eeed290c9fb73f732af1f7d6b0a703e, 1b4c03f8892d955385c202009af7485364731bb9, 654386baef228c2992dbf604c819e4c7c35fc71b, 75fe6db23705a1d55160081f7b37db9665b1880b, d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6, ceccbfc6de720ad633519a226715989cfb065af1, 42156f93d123436f2a27c468f18c966b7e5db796 |
| Linux/Linuxgeneric | 3.1 | 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 22, 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: fix fanout UAF in packet_release() via NETDEV_UP race `packet_release()` has a race window where `NETDEV_UP` can re-register a socket into a fanout group's `arr[]` array. The re-registration is not cleaned up by `fanout_release()`, leaving a dangling pointer in the fanout array. `packet_release()` does NOT zero `po->num` in its `bind_lock` section. After releasing `bind_lock`, `po->num` is still non-zero and `po->ifindex` still matches the bound device. A concurrent `packet_notifier(NETDEV_UP)` that already found the socket in `sklist` can re-register the hook. For fanout sockets, this re-registration calls `__fanout_link(sk, po)` which adds the socket back into `f->arr[]` and increments `f->num_members`, but does NOT increment `f->sk_ref`. The fix sets `po->num` to zero in `packet_release` while `bind_lock` is held to prevent NETDEV_UP from linking, preventing the race window. This bug was found following an additional audit with Claude Code based on CVE-2025-38617.
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 | >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <ee642b1962caa9aa231c01abbd58bc453ae6b66e || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <42cfd7898eeed290c9fb73f732af1f7d6b0a703e || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <1b4c03f8892d955385c202009af7485364731bb9 || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <654386baef228c2992dbf604c819e4c7c35fc71b || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <75fe6db23705a1d55160081f7b37db9665b1880b || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6 || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <ceccbfc6de720ad633519a226715989cfb065af1 || >=ce06b03e60fc19c680d1bf873e779bf11c2fc518 <42156f93d123436f2a27c468f18c966b7e5db796 | ee642b1962caa9aa231c01abbd58bc453ae6b66e, 42cfd7898eeed290c9fb73f732af1f7d6b0a703e, 1b4c03f8892d955385c202009af7485364731bb9, 654386baef228c2992dbf604c819e4c7c35fc71b, 75fe6db23705a1d55160081f7b37db9665b1880b, d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6, ceccbfc6de720ad633519a226715989cfb065af1, 42156f93d123436f2a27c468f18c966b7e5db796 |
| Linux/Linuxgeneric | 3.1 | 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 22, 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: fix fanout UAF in packet_release() via NETDEV_UP race `packet_release()` has a race window where `NETDEV_UP` can re-register a socket into a fanout group's `arr[]` array. The re-registration is not cleaned up by `fanout_release()`, leaving a dangling pointer in the fanout array. `packet_release()` does NOT zero `po->num` in its `bind_lock` section. After releasing `bind_lock`, `po->num` is still non-zero and `po->ifindex` still matches the bound device. A concurrent `packet_notifier(NETDEV_UP)` that already found the socket in `sklist` can re-register the hook. For fanout sockets, this re-registration calls `__fanout_link(sk, po)` which adds the socket back into `f->arr[]` and increments `f->num_members`, but does NOT increment `f->sk_ref`. The fix sets `po->num` to zero in `packet_release` while `bind_lock` is held to prevent NETDEV_UP from linking, preventing the race window. This bug was found following an additional audit with Claude Code based on CVE-2025-38617.
Quoted source text, attributed separately from HOL analysis.