Security readout for executives and security teams
Plain-English summary
ARM mbed 6.3.0 has an integer wraparound flaw in memory allocation handling. In affected embedded products, crafted network-reachable input could potentially cause crashes or remote code execution. The source bundle does not show confirmed active exploitation.
Executive priority
Treat this as a high-priority embedded software exposure, not a confirmed emergency exploitation event. Focus first on discovering where ARM mbed 6.3.0 exists, then push vendor-confirmed firmware updates or isolation for externally reachable devices.
Technical view
CVE-2021-27435 is a CWE-190 integer overflow or wraparound in ARM mbed 6.3.0 malloc_wrapper. The CVSS 3.1 score is 7.3, network exploitable, low complexity, unauthenticated, and no user interaction. Reported impacts are limited confidentiality, integrity, and availability loss.
Likely exposure
Exposure is most likely in embedded, IoT, or industrial products built with ARM mbed 6.3.0. Business exposure depends on whether deployed firmware includes that version and exposes code paths that can reach the vulnerable allocation behavior.
Exploitation context
The bundle does not cite CISA KEV listing or any confirmed in-the-wild exploitation. The CVSS vector indicates remote unauthenticated exploitability is plausible, but available evidence here does not prove active exploitation or provide affected downstream products.
Researcher notes
Key evidence is limited to the CVE record, CISA ICS advisory, and ARM mbed pull request reference. Do not generalize beyond ARM mbed 6.3.0 without downstream vendor confirmation. Track PR 14408 and release notes for exact remediation lineage.
Mitigation direction
- Inventory firmware and dependencies for ARM mbed 6.3.0.
- Review ARM mbed pull request 14408 and vendor release guidance.
- Upgrade affected firmware when a vendor-supported fixed version is confirmed.
- Prioritize network-exposed embedded and OT devices first.
- Apply compensating network controls where firmware cannot be updated quickly.
Validation and detection
- Check SBOMs, lockfiles, and source trees for ARM mbed 6.3.0.
- Map products and firmware images that embed ARM mbed.
- Confirm whether exposed services can reach mbed memory allocation paths.
- Review CISA advisory details against deployed device models.
- Document devices awaiting vendor-confirmed remediation.
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 lookupCVE-2021-27435 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
- https://github.com/ARMmbed/mbed-os/pull/14408CVE 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.