Answer in brief
CVE-2025-39931 records a Medium severity (CVSS 5.5) vulnerability in crypto: af_alg - Set merge to zero early in af_alg_sendmsg. 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-2025-39931 records a Medium severity (CVSS 5.5) vulnerability in crypto: af_alg - Set merge to zero early in af_alg_sendmsg. 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 | >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <db2b42425dfbde4983b0c20fb7cfa05f70e6a745 || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <6241b9e2809b12da9130894cf5beddf088dc1b8a || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <2374c11189ef704a3e4863646369f1b8e6a27d71 || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <24c1106504c625fabd3b7229611af617b4c27ac7 || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <045ee26aa3920a47ec46d7fcb302420bf01fd753 || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <9574b2330dbd2b5459b74d3b5e9619d39299fc6f | 28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf, db2b42425dfbde4983b0c20fb7cfa05f70e6a745, 6241b9e2809b12da9130894cf5beddf088dc1b8a, 2374c11189ef704a3e4863646369f1b8e6a27d71, 24c1106504c625fabd3b7229611af617b4c27ac7, 045ee26aa3920a47ec46d7fcb302420bf01fd753, 9574b2330dbd2b5459b74d3b5e9619d39299fc6f |
| Linux/Linuxgeneric | 2.6.38 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| 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/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
Published upstream
Oct 4, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 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: crypto: af_alg - Set merge to zero early in af_alg_sendmsg If an error causes af_alg_sendmsg to abort, ctx->merge may contain a garbage value from the previous loop. This may then trigger a crash on the next entry into af_alg_sendmsg when it attempts to do a merge that can't be done. Fix this by setting ctx->merge to zero near the start of the loop.
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 | >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <db2b42425dfbde4983b0c20fb7cfa05f70e6a745 || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <6241b9e2809b12da9130894cf5beddf088dc1b8a || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <2374c11189ef704a3e4863646369f1b8e6a27d71 || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <24c1106504c625fabd3b7229611af617b4c27ac7 || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <045ee26aa3920a47ec46d7fcb302420bf01fd753 || >=8ff590903d5fc7f5a0a988c38267a3d08e6393a2 <9574b2330dbd2b5459b74d3b5e9619d39299fc6f | 28f6f37abca7c5c9eb3959c66310f1d4d98b8aaf, db2b42425dfbde4983b0c20fb7cfa05f70e6a745, 6241b9e2809b12da9130894cf5beddf088dc1b8a, 2374c11189ef704a3e4863646369f1b8e6a27d71, 24c1106504c625fabd3b7229611af617b4c27ac7, 045ee26aa3920a47ec46d7fcb302420bf01fd753, 9574b2330dbd2b5459b74d3b5e9619d39299fc6f |
| Linux/Linuxgeneric | 2.6.38 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| 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/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
Published upstream
Oct 4, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 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: crypto: af_alg - Set merge to zero early in af_alg_sendmsg If an error causes af_alg_sendmsg to abort, ctx->merge may contain a garbage value from the previous loop. This may then trigger a crash on the next entry into af_alg_sendmsg when it attempts to do a merge that can't be done. Fix this by setting ctx->merge to zero near the start of the loop.
Quoted source text, attributed separately from HOL analysis.