Security readout for executives and security teams
Plain-English summary
CVE-2021-27421 is an integer overflow in NXP MCUXpresso SDK before 2.8.2. Products built with affected SDK code may allocate memory incorrectly, causing out-of-bounds memory access and crashes or limited data and integrity impact. The sources do not identify specific finished devices.
Executive priority
Treat this as a high-priority embedded supply-chain issue where NXP SDK use is confirmed. The main business risk is vulnerable firmware remaining deployed in operational devices without clear inventory or update ownership.
Technical view
The issue is CWE-190 in SDK_Malloc. A crafted allocation size can wrap integer arithmetic, leading to heap allocation behavior outside expected bounds. CVSS 3.1 is 7.3 with network attack vector, low complexity, no privileges, and no user interaction.
Likely exposure
Exposure is most likely in embedded, IoT, or industrial firmware built with NXP MCUXpresso SDK versions prior to 2.8.2. Actual risk depends on whether SDK_Malloc is included and reachable through attacker-controlled input.
Exploitation context
CISA KEV is false for this CVE, and the provided sources do not report active exploitation. The CVSS vector indicates unauthenticated network reachability is possible, but exploit maturity and real-world targeting are not established in the bundle.
Researcher notes
The public record names the SDK and vulnerable version range, but not downstream device models. Validation should focus on SDK provenance, compiled code presence, and reachable allocation paths. Avoid assuming exploitability for every product using the SDK.
Mitigation direction
- Identify products or firmware built with MCUXpresso SDK before 2.8.2.
- Upgrade or rebuild with MCUXpresso SDK 2.8.2 or later.
- Follow NXP and CISA advisory guidance for affected deployments.
- Limit network access to exposed embedded devices until firmware is updated.
- Prioritize externally reachable or safety-critical systems first.
Validation and detection
- Check SBOMs, build manifests, or source trees for MCUXpresso SDK version.
- Confirm whether SDK_Malloc is compiled into shipped firmware.
- Map external input paths that can influence allocation sizes.
- Verify deployed firmware versions after remediation.
- Document products where SDK version 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 lookupCVE-2021-27421 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://mcuxpresso.nxp.com/en/welcomeCVE 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.