Security readout for executives and security teams
Plain-English summary
This flaw affects ARM’s mbed-ualloc memory library version 1.3.0. A memory allocation calculation can wrap around, causing unsafe allocation behavior. Public sources say outcomes may include crashes or remote code execution. The main business concern is embedded or ICS products that include this vulnerable library.
Executive priority
Treat this as high priority for embedded and ICS environments, especially internet-reachable or safety-relevant systems. If the organization does not use ARM mbed-ualloc 1.3.0 directly or through suppliers, urgency is lower but should be confirmed through inventory.
Technical view
CVE-2021-27433 is a CWE-190 integer overflow or wraparound in ARM mbed-ualloc 1.3.0, specifically in mbed_krbs. The CVSS 3.1 score is 7.3 with network attack vector, low complexity, no privileges, and no user interaction. The bundle names no CPEs or downstream affected products.
Likely exposure
Exposure is most likely where embedded, IoT, or ICS firmware includes ARM mbed-ualloc 1.3.0. The provided evidence identifies the library version, not specific commercial products, devices, or cloud services.
Exploitation context
The sources describe potential crash or remote code injection/execution, but the bundle does not show active exploitation. CISA KEV status is false, and no cited source in the bundle claims exploitation in the wild.
Researcher notes
Evidence is specific to ARM mbed-ualloc 1.3.0 and mbed_krbs. The bundle does not provide exploit details, affected CPEs, downstream product mapping, or confirmed in-the-wild exploitation. Use supplier confirmation and dependency evidence before declaring systems affected.
Mitigation direction
- Identify products or firmware using ARM mbed-ualloc 1.3.0.
- Check ARM, CISA, and downstream vendor guidance for corrected builds.
- Prioritize updating or rebuilding affected components when vendor-supported fixes are available.
- Reduce network exposure for devices that may contain the vulnerable library.
- Track supplier advisories for firmware using ARM mbed-ualloc.
Validation and detection
- Review SBOMs, build manifests, and source dependencies for mbed-ualloc 1.3.0.
- Ask vendors whether their firmware includes ARM mbed-ualloc 1.3.0.
- Confirm affected devices are not unnecessarily reachable from untrusted networks.
- Verify remediation by confirming the vulnerable library version is absent.
- Document any unknown firmware dependencies as residual exposure.
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-2021-27433 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.