CVE-2021-27435

FAUCET Score

CVE-2021-27435 is a critical integer wrap-around vulnerability in the malloc_wrapper function of ARM mbed product Version 6.3.0. This flaw allows for arbitrary memory allocation, potentially leading to system crashes or remote code execution. With a CVSS score of 9.8, it presents a severe risk due to its network-based attack vector, low attack complexity, and complete compromise of confidentiality, integrity, and availability. While no active exploitation, public exploit code, or significant community discussion has been observed, the high FAUCET Risk Score of 83/100 indicates its serious potential.

Impacted Technologies

Vendor	Product	Version(s)	CPE
		6.3.0CPE matchmatch criteria	cpe:2.3:o:arm:mbed:6.3.0:::::::*

CVSS Data

CVSS version used by this source: 3.1

7.3HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

LOW

Exploitability Score

3.9

Impact Score

3.4

CvssVersion

3.1

Exploit Intelligence

EPSS Score

1.74%

Probability of exploitation in next 30 days

EPSS Percentile

75.4%

Percentile rank of EPSS score among Peer Group

As of 2026-07-27

Model: v2026.06.15

This CVE's current EPSS score of 0.0174 is in the 63rd percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference

View patch

References

github.com / ARMmbed/mbed-os/pull/14408

ExploitIssue TrackingPatchThird Party Advisory

cisa.gov / uscert/ics/advisories/icsa-21-119-04

Third Party AdvisoryUS Government Resource