CVE-2025-40300: x86/vmscape: Add conditional IBPB mitigation
Noroxi assessment
Priority: Monitor (action score 22/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.37% (FIRST EPSS).
- Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: Linux Linux 15006289e5c38b2a830e1fba221977a27598176c, 2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e, 2f8f173413f1cbf52660d04df92d0069c4306d25; azl3 kernel 6.6.104.2-4 on Azure Linux 3.0 6.6.112.1-1; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1.
Low priority for now. Upgrade to Linux Linux 15006289e5c38b2a830e1fba221977a27598176c, 2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e, 2f8f173413f1cbf52660d04df92d0069c4306d25; azl3 kernel 6.6.104.2-4 on Azure Linux 3.0 6.6.112.1-1; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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 ]
- BDU:2025-15665
- ALSA-2025:19930
- ALSA-2025:19931
- ALSA-2025:19932
- openSUSE-SU-2025:15553-1
- RHSA-2025:19930
- RHSA-2025:19931
- RHSA-2025:19932
- RHSA-2025:21112
- RHSA-2025:21118
- RHSA-2025:21760
- RHSA-2025:22006
- RHSA-2025:22066
- RHSA-2025:22072
- RHSA-2025:22087
- RHSA-2025:22095
- RHSA-2025:22124
- RHSA-2026:0271
- RLSA-2025:19931
- RLSA-2025:19932
- Published
- Sep 11, 2025
- Updated
- Oct 19, 2026
- EPSS
- 0.3% · 32th percentile
- CWE
- —
Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 22 / 40 · 5.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.3%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| linux | linux kernel | cpe:2.3:o:linux:linux_kernel |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux11.0
- linux linux kernel4.4.168 and later · before 4.5
- linux linux kernel4.16 and later · before 5.10.244
- linux linux kernel5.11 and later · before 5.15.193
- linux linux kernel5.16 and later · before 6.1.152
- linux linux kernel3.16.57 and later · before 3.17
- linux linux kernel6.7 and later · before 6.12.47
- linux linux kernel6.13 and later · before 6.16.7
- linux linux kernel6.2 and later · before 6.6.106
- linux linux kernel6.17
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- c51f1e5f57cca88d8d5894b6fad1638f643a99d0, 4b3870c343a82cd2df7192cc5149c87205dcc611, 4.16affected
- 15d45071523d89b3fb7372e2135fbd72f6af9506 and later · before ac60717f9a8d21c58617d0b34274babf24135835affected · git
- 15d45071523d89b3fb7372e2135fbd72f6af9506 and later · before c08192b5d6730a914dee6175bc71092ee6a65f14affected · git
- 15d45071523d89b3fb7372e2135fbd72f6af9506 and later · before d5490dfa35427a2967e00a4c7a1b95fdbc8ede34affected · git
- 15d45071523d89b3fb7372e2135fbd72f6af9506 and later · before 2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6eaffected · git
- 15d45071523d89b3fb7372e2135fbd72f6af9506 and later · before 15006289e5c38b2a830e1fba221977a27598176caffected · git
- 15d45071523d89b3fb7372e2135fbd72f6af9506 and later · before 893387c18612bb452336a5881da0d015a7e8f4a2affected · git
- 15d45071523d89b3fb7372e2135fbd72f6af9506 and later · before f866eef8d1c65504d30923c3f14082ad294d0e6daffected · git
- 15d45071523d89b3fb7372e2135fbd72f6af9506 and later · before 34e5667041050711a947e260fc9ebebe08bddee5affected · git
- 15d45071523d89b3fb7372e2135fbd72f6af9506 and later · before d7ddc93392e4a7ffcccc86edf6ef3e64c778db52affected · git
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:8 | bpftool | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-abi-stablelists | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-core | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-cross-headers | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-debug | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-debug-core | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-debug-devel | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-debug-modules | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-debug-modules-extra | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-devel | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-doc | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-headers | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-modules | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-modules-extra | before 4.18.0-553.83.1.el8_10 | 4.18.0-553.83.1.el8_10 |
| AlmaLinux:8 | kernel-rt | before 4.18.0-553.83.1.rt7.424.el8_10 | 4.18.0-553.83.1.rt7.424.el8_10 |
| AlmaLinux:8 | kernel-rt-core | before 4.18.0-553.83.1.rt7.424.el8_10 | 4.18.0-553.83.1.rt7.424.el8_10 |
| AlmaLinux:8 | kernel-rt-debug | before 4.18.0-553.83.1.rt7.424.el8_10 | 4.18.0-553.83.1.rt7.424.el8_10 |
| AlmaLinux:8 | kernel-rt-debug-core | before 4.18.0-553.83.1.rt7.424.el8_10 | 4.18.0-553.83.1.rt7.424.el8_10 |
| AlmaLinux:8 | kernel-rt-debug-devel | before 4.18.0-553.83.1.rt7.424.el8_10 | 4.18.0-553.83.1.rt7.424.el8_10 |
| AlmaLinux:8 | kernel-rt-debug-modules | before 4.18.0-553.83.1.rt7.424.el8_10 | 4.18.0-553.83.1.rt7.424.el8_10 |
| AlmaLinux:8 | kernel-rt-debug-modules-extra | before 4.18.0-553.83.1.rt7.424.el8_10 | 4.18.0-553.83.1.rt7.424.el8_10 |
| AlmaLinux:8 | kernel-rt-devel | before 4.18.0-553.83.1.rt7.424.el8_10 | 4.18.0-553.83.1.rt7.424.el8_10 |
| AlmaLinux:8 | kernel-rt-modules | before 4.18.0-553.83.1.rt7.424.el8_10 | 4.18.0-553.83.1.rt7.424.el8_10 |
+96
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV90Now
- CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV89Now
- CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV85Now
Published before and after this one in the same product
- ← EarlierCVE-2025-39790Sep 11, 2025 · bus: mhi: host: Detect events pointing to unexpected TREs31Monitor
- ← EarlierCVE-2025-39791Sep 11, 2025 · dm: dm-crypt: Do not partially accept write BIOs with zoned targets22Monitor
- Later →CVE-2025-39792Sep 12, 2025 · dm: Always split write BIOs to zoned device limits22Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 15006289e5c38b2a830e1fba221977a27598176c | Vendor (CNA) |
| Linux Linux | 2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e | Vendor (CNA) |
| Linux Linux | 2f8f173413f1cbf52660d04df92d0069c4306d25 | Vendor (CNA) |
| Linux Linux | 3.17 | Vendor (CNA) |
| Linux Linux | 34e5667041050711a947e260fc9ebebe08bddee5 | Vendor (CNA) |
| Linux Linux | 4.5 | Vendor (CNA) |
| Linux Linux | 459274c77b37ac63b78c928b4b4e748d1f9d05c8 | Vendor (CNA) |
| Linux Linux | 510603f504796c3535f67f55fb0b124a303b44c8 | Vendor (CNA) |
| Linux Linux | 893387c18612bb452336a5881da0d015a7e8f4a2 | Vendor (CNA) |
| Linux Linux | 9c23a90648e831d611152ac08dbcd1283d405e7f | Vendor (CNA) |
| Linux Linux | ac60717f9a8d21c58617d0b34274babf24135835 | Vendor (CNA) |
| Linux Linux | c08192b5d6730a914dee6175bc71092ee6a65f14 | Vendor (CNA) |
| Linux Linux | d5490dfa35427a2967e00a4c7a1b95fdbc8ede34 | Vendor (CNA) |
| Linux Linux | d7ddc93392e4a7ffcccc86edf6ef3e64c778db52 | Vendor (CNA) |
| Linux Linux | f866eef8d1c65504d30923c3f14082ad294d0e6d | Vendor (CNA) |
| azl3 kernel 6.6.104.2-4 on Azure Linux 3.0 | 6.6.112.1-1 · CBL-Mariner Releases | Microsoft (MSRC) |
| cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 | 5.15.200.1-1 · CBL-Mariner Releases | Microsoft (MSRC) |
| almalinux:kernel | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-core | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-debug | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-debug-core | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-debug-devel | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-debug-devel-matched | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-debug-modules | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-debug-modules-core | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-debug-modules-extra | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-devel | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:kernel-64k-devel-matched | 5.14.0-570.62.1.el9_6 · AlmaLinux:9 | Package registry (OSV) |
| debian:linux | 6.1.153-1 · Debian:12 | Package registry (OSV) |
+15
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
—
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (19 more)Show less
- git.kernel.org/stable/c/2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e
- git.kernel.org/stable/c/2f8f173413f1cbf52660d04df92d0069c4306d25
- git.kernel.org/stable/c/34e5667041050711a947e260fc9ebebe08bddee5
- git.kernel.org/stable/c/459274c77b37ac63b78c928b4b4e748d1f9d05c8
- git.kernel.org/stable/c/510603f504796c3535f67f55fb0b124a303b44c8
- git.kernel.org/stable/c/893387c18612bb452336a5881da0d015a7e8f4a2
- git.kernel.org/stable/c/9c23a90648e831d611152ac08dbcd1283d405e7f
- git.kernel.org/stable/c/ac60717f9a8d21c58617d0b34274babf24135835
- git.kernel.org/stable/c/c08192b5d6730a914dee6175bc71092ee6a65f14
- git.kernel.org/stable/c/d5490dfa35427a2967e00a4c7a1b95fdbc8ede34
- git.kernel.org/stable/c/d7ddc93392e4a7ffcccc86edf6ef3e64c778db52
- git.kernel.org/stable/c/f866eef8d1c65504d30923c3f14082ad294d0e6d
- www.openwall.com/lists/oss-security/2025/11/14/3
- www.openwall.com/lists/oss-security/2025/11/14/4
- www.openwall.com/lists/oss-security/2025/11/14/6
- www.openwall.com/lists/oss-security/2025/11/17/2
- www.openwall.com/lists/oss-security/2025/11/17/3
- lists.debian.org/debian-lts-announce/2025/10/msg00007.html
- lists.debian.org/debian-lts-announce/2025/10/msg00008.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.