Answer in brief
CVE-2025-40300 records a Medium severity (CVSS 5.5) vulnerability in x86/vmscape: Add conditional IBPB mitigation. 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-2025-40300 records a Medium severity (CVSS 5.5) vulnerability in x86/vmscape: Add conditional IBPB mitigation. 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 | >=15d45071523d89b3fb7372e2135fbd72f6af9506 <ac60717f9a8d21c58617d0b34274babf24135835 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <c08192b5d6730a914dee6175bc71092ee6a65f14 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <d5490dfa35427a2967e00a4c7a1b95fdbc8ede34 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <15006289e5c38b2a830e1fba221977a27598176c || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <893387c18612bb452336a5881da0d015a7e8f4a2 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <f866eef8d1c65504d30923c3f14082ad294d0e6d || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <34e5667041050711a947e260fc9ebebe08bddee5 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <d7ddc93392e4a7ffcccc86edf6ef3e64c778db52 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <459274c77b37ac63b78c928b4b4e748d1f9d05c8 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <510603f504796c3535f67f55fb0b124a303b44c8 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <9c23a90648e831d611152ac08dbcd1283d405e7f || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <2f8f173413f1cbf52660d04df92d0069c4306d25 || c51f1e5f57cca88d8d5894b6fad1638f643a99d0 || 4b3870c343a82cd2df7192cc5149c87205dcc611 || >=3.16.57 <3.17 || >=4.4.168 <4.5 | ac60717f9a8d21c58617d0b34274babf24135835, c08192b5d6730a914dee6175bc71092ee6a65f14, d5490dfa35427a2967e00a4c7a1b95fdbc8ede34, 2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e, 15006289e5c38b2a830e1fba221977a27598176c, 893387c18612bb452336a5881da0d015a7e8f4a2, f866eef8d1c65504d30923c3f14082ad294d0e6d, 34e5667041050711a947e260fc9ebebe08bddee5, d7ddc93392e4a7ffcccc86edf6ef3e64c778db52, 459274c77b37ac63b78c928b4b4e748d1f9d05c8, 510603f504796c3535f67f55fb0b124a303b44c8, 9c23a90648e831d611152ac08dbcd1283d405e7f, 2f8f173413f1cbf52660d04df92d0069c4306d25, 3.17, 4.5 |
| Linux/Linuxgeneric | 4.16 | 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 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: x86/vmscape: Add conditional IBPB mitigation VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing mitigations already protect kernel/KVM from a malicious guest. Userspace can additionally be protected by flushing the branch predictors after a VMexit. Since it is the userspace that consumes the poisoned branch predictors, conditionally issue an IBPB after a VMexit and before returning to userspace. Workloads that frequently switch between hypervisor and userspace will incur the most overhead from the new IBPB. This new IBPB is not integrated with the existing IBPB sites. For instance, a task can use the existing speculation control prctl() to get an IBPB at context switch time. With this implementation, the IBPB is doubled up: one at context switch and another before running userspace. The intent is to integrate and optimize these cases post-embargo. [ dhansen: elaborate on suboptimal IBPB solution ]
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 | >=15d45071523d89b3fb7372e2135fbd72f6af9506 <ac60717f9a8d21c58617d0b34274babf24135835 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <c08192b5d6730a914dee6175bc71092ee6a65f14 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <d5490dfa35427a2967e00a4c7a1b95fdbc8ede34 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <15006289e5c38b2a830e1fba221977a27598176c || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <893387c18612bb452336a5881da0d015a7e8f4a2 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <f866eef8d1c65504d30923c3f14082ad294d0e6d || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <34e5667041050711a947e260fc9ebebe08bddee5 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <d7ddc93392e4a7ffcccc86edf6ef3e64c778db52 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <459274c77b37ac63b78c928b4b4e748d1f9d05c8 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <510603f504796c3535f67f55fb0b124a303b44c8 || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <9c23a90648e831d611152ac08dbcd1283d405e7f || >=15d45071523d89b3fb7372e2135fbd72f6af9506 <2f8f173413f1cbf52660d04df92d0069c4306d25 || c51f1e5f57cca88d8d5894b6fad1638f643a99d0 || 4b3870c343a82cd2df7192cc5149c87205dcc611 || >=3.16.57 <3.17 || >=4.4.168 <4.5 | ac60717f9a8d21c58617d0b34274babf24135835, c08192b5d6730a914dee6175bc71092ee6a65f14, d5490dfa35427a2967e00a4c7a1b95fdbc8ede34, 2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e, 15006289e5c38b2a830e1fba221977a27598176c, 893387c18612bb452336a5881da0d015a7e8f4a2, f866eef8d1c65504d30923c3f14082ad294d0e6d, 34e5667041050711a947e260fc9ebebe08bddee5, d7ddc93392e4a7ffcccc86edf6ef3e64c778db52, 459274c77b37ac63b78c928b4b4e748d1f9d05c8, 510603f504796c3535f67f55fb0b124a303b44c8, 9c23a90648e831d611152ac08dbcd1283d405e7f, 2f8f173413f1cbf52660d04df92d0069c4306d25, 3.17, 4.5 |
| Linux/Linuxgeneric | 4.16 | 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 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: x86/vmscape: Add conditional IBPB mitigation VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing mitigations already protect kernel/KVM from a malicious guest. Userspace can additionally be protected by flushing the branch predictors after a VMexit. Since it is the userspace that consumes the poisoned branch predictors, conditionally issue an IBPB after a VMexit and before returning to userspace. Workloads that frequently switch between hypervisor and userspace will incur the most overhead from the new IBPB. This new IBPB is not integrated with the existing IBPB sites. For instance, a task can use the existing speculation control prctl() to get an IBPB at context switch time. With this implementation, the IBPB is doubled up: one at context switch and another before running userspace. The intent is to integrate and optimize these cases post-embargo. [ dhansen: elaborate on suboptimal IBPB solution ]
Quoted source text, attributed separately from HOL analysis.