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Improper Access ControlWeakness · CWE-284

CVE-2025-29939

MEDIUM · 6.9 CVSS v4.0 Published 2026-02-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
71/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Improper access control in secure encrypted virtualization (SEV) could allow a privileged attacker to write to the reverse map page (RMP) during secure nested paging (SNP) initialization, potentially resulting in a loss of guest memory confidentiality and integrity.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

This is a vulnerability in AMD Secure Encrypted Virtualization (SEV) with Secure Nested Paging (SNP). During SNP initialization, improper access controls allow a privileged attacker to write to the Reverse Map Page (RMP), potentially compromising guest VM memory confidentiality and integrity.

MitigationApply AMD-provided firmware/microcode updates for SEV-SNP and ensure BIOS updates from system vendors are deployed. Verify SEV functionality after updates.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
High
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if CPU supports AMD SEV-SNP
    Run 'grep -o sev-snp /proc/cpuinfo' or check 'cpuid | grep -i sev' to see if the CPU has SEV-SNP capability flags
    Affected if If no SEV-SNP support is present, the system is not vulnerable to this specific SNP initialization flaw
  2. Verify SEV-SNP is enabled in the system
    Check /sys/kernel/debug/sev-SNP or run 'kvmstat -l | grep sev-snp' to see if SEV-SNP is actively used
    Affected if If SEV-SNP is not enabled or initialized, the attack surface does not exist for this specific flaw
  3. Check BIOS/UEFI SEV settings
    Access BIOS/UEFI setup and look for 'SEV', 'SEV-ES', or 'SEV-SNP' enablement options under processor or security settings
    Affected if If SEV-SNP is disabled in BIOS, the vulnerability does not apply as SNP initialization never occurs
  4. Query AMD SEV firmware version
    Run 'dmesg | grep -i sev' or check /sys/firmware/efi/efivars for SEV-SNP status; compare the reported firmware version against AMD-provided SNP firmware releases
    Affected if If the firmware version is older than AMD's patched SEV-SNP microcode releases, the system may be affected
  5. Check kernel SEV-SNP support
    Run 'cat /proc/cmdline' and look for 'mem_encrypt=on' or 'sev-snp' kernel parameters, and verify the kernel version supports SEV-SNP (kernel 5.10+ with CONFIG_AMD_MEM_ENCRYPT_ACTIVE)
    Affected if If kernel lacks SEV-SNP support and the feature is not initialized, the specific flaw cannot be exploited

A system is affected only if it has AMD SEV-SNP-capable hardware, has SEV-SNP enabled in BIOS and the OS, and is running firmware versions prior to AMD's patched SEV-SNP microcode releases.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply AMD-provided firmware/microcode updates for SEV-SNP and ensure BIOS updates from system vendors are deployed. Verify SEV functionality after updates.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-29939 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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