CVE-2021-27431: ARM CMSIS RTOS2 Integer Overflow or Wraparound
Noroxi assessment
Priority: Monitor (action score 39/100)
- 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: 1.1% (FIRST EPSS); higher than 67.2% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- According to the record, no fixed version is available yet.
- Severity is disputed: the assigning authority (CNA) scores it 7.3, NVD 9.8.
Low priority for now. Update when a fix is released; follow the vendor's advisory.
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
ARM CMSIS RTOS2 versions prior to 2.1.3 are vulnerable to integer wrap-around inosRtxMemoryAlloc (local malloc equivalent) function, which can lead to arbitrary memory allocation, resulting in unexpected behavior such as a crash or injected code execution.
- Published
- May 3, 2022
- Updated
- Jun 16, 2026
- EPSS
- 1.1% · 67th percentile
- CWE
- CWE-190
Report tools
Action score
39
Low priority for now.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.1%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 9.8
- CNA · icscert
- 7.3
- 2.5 point gap
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- No fixed version yet
If any of these changes, we'll tell you in the daily email digest.
Is your version affected? Check itNoroxi 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 |
|---|---|---|
| arm | cmsis-rtos | cpe:2.3:o:arm:cmsis-rtos |
Versions reported by the vendor
Affected version ranges reported by the assigning authority (icscert). Independent of NVD's CPE analysis and usually ahead of it.
ARM CMSIS RTOS2
- unspecified and later · before 2.1.3affected
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- arm cmsis-rtosup to 2.1.3 inclusive
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
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.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- David Atch, Omri Ben Bassat, and Tamir ArielMicrosoft Section 52, and the Azure Defender for IoT research group reported these vulnerabilities to CISA.
Bug bounty scope
The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.
Not on record for this CVE: EPSS history · patch commit or PR link · variant or chain candidate.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-190 · Integer Overflow or WraparoundCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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.
Attack patterns (CAPEC)
ATT&CK techniques
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Change log (0)
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.