Answer in brief
CVE-2025-38732 records a Medium severity (CVSS 5.5) vulnerability in netfilter: nf_reject: don't leak dst refcount for loopback packets. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC CN 4100 (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-2025-38732 records a Medium severity (CVSS 5.5) vulnerability in netfilter: nf_reject: don't leak dst refcount for loopback packets. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC CN 4100 (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 CN 4100 (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 | >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <82ef97abf22790182f7d433c74960dfd61b99c33 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <b7a885ba25960c91db237c3f83b4285156789bce || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <a0a3ace2a57887dac1e7c9a724846040c3e31868 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <51e8531371f90bee742c63775c9a568e5d6bf3c5 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <b32e1590a8d22cf7d7f965e46d5576051acf8e42 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <91a79b792204313153e1bdbbe5acbfc28903b3a5 | 7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8, 82ef97abf22790182f7d433c74960dfd61b99c33, b7a885ba25960c91db237c3f83b4285156789bce, a0a3ace2a57887dac1e7c9a724846040c3e31868, 51e8531371f90bee742c63775c9a568e5d6bf3c5, b32e1590a8d22cf7d7f965e46d5576051acf8e42, 91a79b792204313153e1bdbbe5acbfc28903b3a5 |
| Linux/Linuxgeneric | 5.9 | Not reported |
| Siemens/SIMATIC CN 4100generic | >=0 <V5.0 | V5.0 |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
Published upstream
Sep 5, 2025
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_reject: don't leak dst refcount for loopback packets recent patches to add a WARN() when replacing skb dst entry found an old bug: WARNING: include/linux/skbuff.h:1165 skb_dst_check_unset include/linux/skbuff.h:1164 [inline] WARNING: include/linux/skbuff.h:1165 skb_dst_set include/linux/skbuff.h:1210 [inline] WARNING: include/linux/skbuff.h:1165 nf_reject_fill_skb_dst+0x2a4/0x330 net/ipv4/netfilter/nf_reject_ipv4.c:234 [..] Call Trace: nf_send_unreach+0x17b/0x6e0 net/ipv4/netfilter/nf_reject_ipv4.c:325 nft_reject_inet_eval+0x4bc/0x690 net/netfilter/nft_reject_inet.c:27 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] .. This is because blamed commit forgot about loopback packets. Such packets already have a dst_entry attached, even at PRE_ROUTING stage. Instead of checking hook just check if the skb already has a route attached to it.
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 CN 4100 (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 | >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <82ef97abf22790182f7d433c74960dfd61b99c33 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <b7a885ba25960c91db237c3f83b4285156789bce || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <a0a3ace2a57887dac1e7c9a724846040c3e31868 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <51e8531371f90bee742c63775c9a568e5d6bf3c5 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <b32e1590a8d22cf7d7f965e46d5576051acf8e42 || >=f53b9b0bdc59c0823679f2e3214e0d538f5951b9 <91a79b792204313153e1bdbbe5acbfc28903b3a5 | 7b8b503c06274ef3c6c1a107743f1ec0d0a53ef8, 82ef97abf22790182f7d433c74960dfd61b99c33, b7a885ba25960c91db237c3f83b4285156789bce, a0a3ace2a57887dac1e7c9a724846040c3e31868, 51e8531371f90bee742c63775c9a568e5d6bf3c5, b32e1590a8d22cf7d7f965e46d5576051acf8e42, 91a79b792204313153e1bdbbe5acbfc28903b3a5 |
| Linux/Linuxgeneric | 5.9 | Not reported |
| Siemens/SIMATIC CN 4100generic | >=0 <V5.0 | V5.0 |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
Published upstream
Sep 5, 2025
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_reject: don't leak dst refcount for loopback packets recent patches to add a WARN() when replacing skb dst entry found an old bug: WARNING: include/linux/skbuff.h:1165 skb_dst_check_unset include/linux/skbuff.h:1164 [inline] WARNING: include/linux/skbuff.h:1165 skb_dst_set include/linux/skbuff.h:1210 [inline] WARNING: include/linux/skbuff.h:1165 nf_reject_fill_skb_dst+0x2a4/0x330 net/ipv4/netfilter/nf_reject_ipv4.c:234 [..] Call Trace: nf_send_unreach+0x17b/0x6e0 net/ipv4/netfilter/nf_reject_ipv4.c:325 nft_reject_inet_eval+0x4bc/0x690 net/netfilter/nft_reject_inet.c:27 expr_call_ops_eval net/netfilter/nf_tables_core.c:237 [inline] .. This is because blamed commit forgot about loopback packets. Such packets already have a dst_entry attached, even at PRE_ROUTING stage. Instead of checking hook just check if the skb already has a route attached to it.
Quoted source text, attributed separately from HOL analysis.