CVE-2025-5866: RT-Thread · Improper Validation of Array Index
Affects RT-ThreadSource CVE Database V5
Not known to be exploited · CVSS 8.6 High.
Data as of 26 Oct 2026, 10:12 UTC
- EPSS
- 0.8% chance of exploitation in 30 days – higher than 57% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:XExploitation evidence
Disclosed: evidence found.
CVE published 9 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
GitHubrt-thread/rt-threadpkg:github/rt-thread/rt-threadOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
To mitigate the risks posed by CVE-2025-5866, European organizations should take the following specific actions: 1) Identify all devices and systems running RT-Thread version 5.1.0 within their environment, including embedded devices, IoT endpoints, and industrial control systems. 2) Monitor vendor communications and security advisories for the release of patches or updates addressing this vulnerability; apply patches immediately upon availability. 3) If patches are not yet available, implement compensating controls such as network segmentation to isolate vulnerable devices, strict access controls limiting administrative privileges, and enhanced monitoring for anomalous behavior indicative of exploitation attempts. 4) Conduct thorough code audits and security assessments on custom implementations or derivatives of RT-Thread to detect similar improper validation issues. 5) Employ runtime protections such as memory protection units (MPUs) or hardware-enforced isolation where feasible to limit the impact of potential memory corruption. 6) Train operational technology and security teams to recognize signs of exploitation and respond swiftly. 7) Collaborate with device manufacturers and suppliers to ensure timely updates and support for affected embedded systems. These targeted measures go beyond generic advice by focusing on the embedded and operational technology context in which RT-Thread is deployed.
Description
A vulnerability classified as critical has been found in RT-Thread 5.1.0. This affects the function sys_sigprocmask of the file rt-thread/components/lwp/lwp_syscall.c. The manipulation of the argument how leads to improper validation of array index.