8.3

CVE-2026-77236: amazon freertos Out-of-bounds Write

CVSS: 8.3v4.0HighAnalyzed
Published 21-08-2026Last modified 21-08-2026
Open JSON

Vulnerability summary

CVE-2026-77236 is a high (CVSS 8.3) Out-of-bounds Write vulnerability in amazon freertos. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 4.9% of scored vulnerabilities.

Overall risk
33/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.3/10
010
High · v4.0 (CVE.org)
EPSS score
0.16%
0%100%
Low · +0.05 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 21-08-2026
    PublishedVulnerability first disclosed.
  2. 21-08-2026
    Last modifiedVulnerability information updated.

Description

Missing minimum size validation in secure context allocation in FreeRTOS-Kernel before 11.3.1 might allow local users to corrupt secure-world heap metadata via an out-of-bounds write with an undersized stack size parameter. To remediate this issue, users should upgrade to version 11.3.1 or later.

CVSS metrics

4 scores · 2 sources · 2 versions

EPSS trend

Probability

0.16%

Chance of exploitation in the next 30 days

Percentile

5%

Versus all other CVEs

30-day change

+0.05 pp

From 0.11% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.16%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Amazon1 product
Freertos1 product

2 vendors · 2 products

References

3 links