Security readout for executives and security teams
Plain-English summary
This flaw affects GRUB2, a bootloader used before the operating system starts. A malicious USB device could trigger memory corruption during boot-time USB initialization, potentially bypassing Secure Boot and running unauthorized code before normal protections load.
Executive priority
Treat this as high priority for systems where Secure Boot is part of the trust model or physical access is plausible. Prioritize critical servers, workstations, kiosks, and appliances using affected GRUB2 versions, but avoid claiming active exploitation without new evidence.
Technical view
GRUB2 versions prior to 2.06 read USB descriptors with insufficient bounds checking during device initialization. The source describes CWE-787 out-of-bounds write leading to memory corruption, arbitrary code execution, and possible Secure Boot bypass. The bundle provides no CVSS score and no confirmed exploitation evidence.
Likely exposure
Exposure is most likely on systems or appliances using affected GRUB2 bootloader versions and allowing USB device interaction during boot. Linux distributions and vendor appliances should be assessed through their specific advisories because the bundle does not enumerate all affected downstream products.
Exploitation context
The bundle does not show CISA KEV listing or active exploitation. Practical exploitation appears to require interaction with USB initialization during boot, making physical or boot-path access an important exposure factor, but exact attacker prerequisites are not fully detailed in the supplied sources.
Researcher notes
The strongest evidence is the CVE description: USB descriptor parsing lacks bounds checks and can corrupt memory before OS protections apply. Severity metadata is incomplete in the bundle, and downstream impact must be resolved through Red Hat, Fedora, Gentoo, NetApp, or relevant vendor guidance.
Mitigation direction
- Apply GRUB2 updates or bootloader remediation from the relevant OS or appliance vendor.
- Check vendor Secure Boot, shim, and revocation guidance before deploying bootloader changes.
- Restrict physical access to systems where boot-time USB interaction is possible.
- Disable unnecessary USB boot paths where vendor policy and operations allow.
- Track vendor advisories for product-specific impact and deployment caveats.
Validation and detection
- Inventory GRUB2 package and bootloader versions across Linux and appliance fleets.
- Map systems that permit USB devices or USB boot interaction before OS startup.
- Confirm vendor advisories identify the system as affected, fixed, or not impacted.
- Verify bootloader update status after patching, not only OS package status.
- Document exceptions where vendor guidance is unavailable or remediation is deferred.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2020-25647 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.redhat.com/show_bug.cgi?id=1886936CVE reference · x_refsource_MISC
- FEDORA-2021-cab258a413CVE reference · vendor-advisory, x_refsource_FEDORA
- GLSA-202104-05CVE reference · vendor-advisory, x_refsource_GENTOO
- https://security.netapp.com/advisory/ntap-20220325-0001/CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.