Answer in brief
CVE-2025-39764 records a Medium severity (CVSS 5.5) vulnerability in netfilter: ctnetlink: remove refcounting in expectation dumpers. 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-2025-39764 records a Medium severity (CVSS 5.5) vulnerability in netfilter: ctnetlink: remove refcounting in expectation dumpers. 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 | >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <b05500444b8eb97644efdd180839a04a706be97c || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <bada48ad5b0590e318d0f79636ff62a2ef9f4955 || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <64b7684042246e3238464c66894e30ba30c7e851 || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <9e5021a906532ca16e2aac69c0607711e1c70b1f || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <078d33c95bf534d37aa04269d1ae6158e20082d5 || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <a4d634ded4d3d400f115d84f654f316f249531c9 || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <1492e3dcb2be3aa46d1963da96aa9593e4e4db5a | b05500444b8eb97644efdd180839a04a706be97c, bada48ad5b0590e318d0f79636ff62a2ef9f4955, 64b7684042246e3238464c66894e30ba30c7e851, 9e5021a906532ca16e2aac69c0607711e1c70b1f, 078d33c95bf534d37aa04269d1ae6158e20082d5, a4d634ded4d3d400f115d84f654f316f249531c9, 1492e3dcb2be3aa46d1963da96aa9593e4e4db5a |
| Linux/Linuxgeneric | 2.6.23 | 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
Sep 11, 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: ctnetlink: remove refcounting in expectation dumpers Same pattern as previous patch: do not keep the expectation object alive via refcount, only store a cookie value and then use that as the skip hint for dump resumption. AFAICS this has the same issue as the one resolved in the conntrack dumper, when we do if (!refcount_inc_not_zero(&exp->use)) to increment the refcount, there is a chance that exp == last, which causes a double-increment of the refcount and subsequent memory leak.
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 | >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <b05500444b8eb97644efdd180839a04a706be97c || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <bada48ad5b0590e318d0f79636ff62a2ef9f4955 || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <64b7684042246e3238464c66894e30ba30c7e851 || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <9e5021a906532ca16e2aac69c0607711e1c70b1f || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <078d33c95bf534d37aa04269d1ae6158e20082d5 || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <a4d634ded4d3d400f115d84f654f316f249531c9 || >=cf6994c2b9812a9f02b99e89df411ffc5db9c779 <1492e3dcb2be3aa46d1963da96aa9593e4e4db5a | b05500444b8eb97644efdd180839a04a706be97c, bada48ad5b0590e318d0f79636ff62a2ef9f4955, 64b7684042246e3238464c66894e30ba30c7e851, 9e5021a906532ca16e2aac69c0607711e1c70b1f, 078d33c95bf534d37aa04269d1ae6158e20082d5, a4d634ded4d3d400f115d84f654f316f249531c9, 1492e3dcb2be3aa46d1963da96aa9593e4e4db5a |
| Linux/Linuxgeneric | 2.6.23 | 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
Sep 11, 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: ctnetlink: remove refcounting in expectation dumpers Same pattern as previous patch: do not keep the expectation object alive via refcount, only store a cookie value and then use that as the skip hint for dump resumption. AFAICS this has the same issue as the one resolved in the conntrack dumper, when we do if (!refcount_inc_not_zero(&exp->use)) to increment the refcount, there is a chance that exp == last, which causes a double-increment of the refcount and subsequent memory leak.
Quoted source text, attributed separately from HOL analysis.