Security readout for executives and security teams
Plain-English summary
This flaw affects embedded software using ARM CMSIS RTOS2 before 2.1.3. A memory allocation integer wraparound can cause crashes or potentially allow injected code execution. Business urgency depends on whether affected RTOS code is present in shipped devices or operational technology systems and reachable through exposed functionality.
Executive priority
Treat this as a high-priority firmware supply-chain issue for connected devices and industrial environments. It is not enough to patch servers; teams need vendor confirmation or firmware evidence for embedded products. Escalate first where devices are remotely reachable or safety-critical.
Technical view
CVE-2021-27431 is a CWE-190 integer overflow or wraparound in CMSIS RTOS2 osRtxMemoryAlloc, described as a local malloc equivalent. The published CVSS 3.1 score is 7.3 with network attack vector, low complexity, no privileges, and no user interaction. Reported impacts are low confidentiality, integrity, and availability loss.
Likely exposure
Likely exposure is embedded, IoT, industrial, or device firmware that includes ARM CMSIS RTOS2 versions before 2.1.3. The source bundle does not identify specific downstream device models, so product-level exposure must be confirmed through firmware SBOMs, vendor notices, or code review.
Exploitation context
The bundle does not show CISA KEV listing or cite active exploitation. The CVSS vector indicates a remotely triggerable condition may be possible where an affected product exposes a path into the vulnerable allocation behavior, but the provided evidence does not describe exploit availability or real-world use.
Researcher notes
Evidence is limited to the CVE metadata and CISA advisory reference in the bundle. The affected product is named only as ARM CMSIS RTOS2 before 2.1.3, with no downstream CPEs or device models provided. Avoid assuming exploitability in any specific product without firmware analysis.
Mitigation direction
- Upgrade ARM CMSIS RTOS2 to version 2.1.3 or later where firmware is maintained internally.
- Ask device vendors whether their firmware includes vulnerable CMSIS RTOS2 versions.
- Prioritize remediation for internet-facing or operational technology devices using affected firmware.
- Follow ARM and CISA advisory guidance for vendor-specific updates or compensating controls.
- Track firmware replacements separately from application patching workflows.
Validation and detection
- Inventory firmware components and SBOMs for CMSIS RTOS2 versions before 2.1.3.
- Confirm whether affected allocation code is compiled into deployed firmware images.
- Map exposed interfaces that could reach RTOS memory allocation from untrusted input.
- Check vendor advisories for product-specific affected versions and fixed firmware.
- Document devices where CMSIS RTOS2 presence cannot be confirmed.
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-190: 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-2021-27431 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
- High
- CVSS
- 7.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
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 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:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L3.93.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.3HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://www.cisa.gov/uscert/ics/advisories/icsa-21-119-04CVE 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.
Integer Overflow or Wraparound
Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.