CVE-2025-5865
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA vulnerability was found in RT-Thread 5.1.0. It has been rated as critical. Affected by this issue is the function sys_select of the file rt-thread/components/lwp/lwp_syscall.c of the component Parameter Handler. The manipulation of the argument timeout leads to memory corruption. The vendor explains, that "[t]he timeout parameter should be checked to check if it can be accessed correctly in kernel mode and used temporarily in kernel memory."
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceA memory corruption vulnerability exists in RT-Thread 5.1.0's sys_select function within the LWP syscall component. The timeout parameter passed from user space is not properly validated before being accessed in kernel mode, allowing an attacker to manipulate the pointer and corrupt kernel memory.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data= 5.1.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check RT-Thread versionIdentify the installed RT-Thread version by checking the version header file (typically rtdef.h or version.h) or by querying the system version at runtime using rt_version() or similar APIAffected if Version is exactly 5.1.0
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Verify LWP syscall component is enabledCheck the RT-Thread configuration (Kconfig or rtconfig.h) for LWP (LightWeight Process) support. Look for options like RT_USING_LWP or CONFIG_LWP being definedAffected if LWP syscall component is compiled into the kernel
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Confirm sys_select is in useInspect the built firmware or source code to determine if the sys_select syscall is implemented and available. Check for select() usage in user applications or the presence of select-related code in the LWP syscall handlerAffected if sys_select function is accessible to user space
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Check timeout parameter handlingExamine the sys_select implementation in the LWP source (typically in lwp_syscall.c or similar) for direct dereferencing of user-space timeout pointers without proper validation or copying to kernel memoryAffected if Code directly accesses user-space timeout pointer without copying it to kernel memory first
User is affected if running RT-Thread version 5.1.0 with the LWP syscall component enabled and using sys_select where user-space timeout pointers are dereferenced directly in kernel mode.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataImplement proper validation of the timeout parameter to verify it can be safely accessed from kernel mode, and copy the parameter to kernel memory before use rather than directly dereferencing the user-space pointer.
- Consultation3.0 h
- Implementation6.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,992.
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Free · runs locallyCheck whether your project pulls in CVE-2025-5865 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-5865 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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