Security readout for executives and security teams
Plain-English summary
CVE-2021-47631 is a Linux kernel reliability flaw in ARM DaVinci DA850 Ethernet initialization. On affected builds, the kernel can dereference a NULL pointer during boot and panic. The business impact is availability, not data theft, and the provided sources do not show active exploitation.
Executive priority
Treat as a targeted availability risk. Prioritize embedded, ARM, or appliance-like systems where reboot failure would disrupt operations. It is less urgent than remotely exploitable kernel bugs, but should be patched through normal kernel maintenance.
Technical view
The flaw is CWE-476 in da850_evm_config_emac(). emac_pdata can be NULL when davinci_soc_info is not populated, because the initcall may run on non-DaVinci machines. The kernel fix moves rmii_en access after the machine check so dereference occurs only for supported SoCs.
Likely exposure
Exposure is most likely on Linux systems using affected ARM DaVinci DA850-related kernel code or multi_v5-style builds. Source data lists Linux kernel as affected across several version lines, but exact exposure depends on downstream kernel patches and configuration.
Exploitation context
The CVSS vector is local, low complexity, low privilege, no user interaction, with high availability impact. The source bundle marks KEV as false and provides no public evidence of active exploitation. The described failure was observed as a boot-time kernel panic in QEMU.
Researcher notes
Evidence supports a NULL pointer dereference fixed by initialization ordering and machine checks. The bundle does not provide exploit code, weaponized scenarios, or distribution-specific fixed package names. Validate against actual kernel configuration and vendor backport status.
Mitigation direction
- Upgrade to a kernel release containing the relevant stable fix for your maintained branch.
- Confirm downstream distribution packages include one of the referenced kernel stable commits.
- Check vendor guidance for exact fixed package versions and backports.
- Reduce local access on systems where vulnerable kernels cannot be updated promptly.
Validation and detection
- Inventory Linux kernel versions and architectures against the affected version data.
- Check kernel source or changelog for the referenced stable commit in your branch.
- Review boot logs for NULL pointer panic in da850_evm_config_emac().
- Confirm test coverage for ARM multi_v5 or DaVinci boot paths after updating.
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-476: 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 lookupCVE-2021-47631 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
- Medium
- CVSS
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/c06f476e5b74bcabb8c4a2fba55864a37e62843bCVE reference, Linux
- https://git.kernel.org/stable/c/a12b356d45cbb6e8a1b718d1436b3d6239a862f3CVE reference, Linux
- https://git.kernel.org/stable/c/c64e2ed5cc376e137e572babfd2edc38b2cfb61bCVE reference, Linux
- https://git.kernel.org/stable/c/89931d4762572aaee6edbe5673d41f8082de110fCVE reference, Linux
- https://git.kernel.org/stable/c/0a312ec66a03133d28570f07bc52749ccfef54daCVE reference, Linux
- https://git.kernel.org/stable/c/0940795c6834fbe7705acc5c3d4b2f7a5f67527aCVE reference, Linux
- https://git.kernel.org/stable/c/c5628533a3ece64235d04fe11ec44d2be99e423dCVE reference, Linux
- https://git.kernel.org/stable/c/83a1cde5c74bfb44b49cb2a940d044bb2380f4eaCVE reference, Linux
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.
NULL Pointer Dereference
NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.