VulnerabilityPublished 18 Jul 2025

CVE-2025-53888: RIOT · Classic Buffer Overflow

Affects RIOTSource CVE Database V5

Not known to be exploited · CVSS 6.6 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 4.0 base score

6.6Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.8% chance of exploitation in 30 days – higher than 58% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

Base metrics

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: High
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Threat metrics

Exploit Maturity: Unreported

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: High: There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.
Exploit Maturity: Unreported: Based on threat intelligence sources each of the following must apply: · No knowledge of publicly available proof-of-concept · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Jul 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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
GitHubriot-os/RIOT`pkg:github/riot-os/RIOT`Other threats	Affected <=2025.04	Fixed in–

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AI-suggested

To mitigate this vulnerability, European organizations should: 1) Immediately update RIOT-OS deployments to versions later than 2025.04 where the patch replacing assert() with proper input validation is applied. 2) Conduct thorough inventory and risk assessments to identify all IoT devices running vulnerable RIOT-OS versions. 3) Implement network segmentation and strict access controls to limit exposure of IoT devices to untrusted networks. 4) Deploy intrusion detection and anomaly monitoring specifically tuned for IoT traffic patterns to detect exploitation attempts. 5) For devices where immediate patching is not feasible, apply compensating controls such as input filtering at gateways or firewalls to prevent malicious addr_len values from reaching vulnerable functions. 6) Engage with device vendors to ensure timely firmware updates and security patches. 7) Incorporate secure development lifecycle practices to avoid reliance on assert() for input validation in future IoT software development.

Description

RIOT-OS, an operating system that supports Internet of Things devices, has an ineffective size check implemented with `assert()` can lead to buffer overflow in versions up to and including 2025.04. Assertions are usually compiled out in production builds. If assertions are the only defense against untrusted inputs, the software may be exposed to attacks that utilize the lack of proper input checks. In the `l2filter_add()` function shown below, `addr_len` is checked using an assertion and is subsequently used as an argument in a `memcpy()` call. When assertions are disabled, there would be no size check for `addr_len`. As a consequence, if an attacker were to provide an `addr_len` value larger than `CONFIG_L2FILTER_ADDR_MAXLEN`, they can trigger a buffer overflow and write past the `list[i].addr` buffer. If the unchecked input is attacker-controlled, the impact of the buffer overflow can range from a denial of service to arbitrary code execution. Commit f6f7de4ccc107c018630e4c15500825caf02e1c2 contains a patch for the vulnerability.

Impact

For European organizations, the impact of CVE-2025-53888 can be substantial, particularly for industries and sectors that deploy RIOT-OS-based IoT devices. These include smart city infrastructure, industrial automation, healthcare devices, and critical infrastructure monitoring systems. Exploitation could lead to denial of service, disrupting essential services, or enable attackers to execute arbitrary code, potentially gaining control over IoT devices. This could facilitate lateral movement within networks, data exfiltration, or sabotage of physical processes. The risk is heightened in environments where devices are exposed to untrusted networks or inputs without adequate perimeter defenses. Given the increasing adoption of IoT in European smart grids, manufacturing, and transportation, the vulnerability could affect operational continuity and safety. Furthermore, compromised IoT devices could be leveraged in botnets or as entry points for broader cyberattacks targeting European organizations.

Summary

CVE-2025-53888 is a medium-severity buffer overflow vulnerability in RIOT-OS, an operating system designed for Internet of Things (IoT) devices. The vulnerability arises from improper input validation in the function l2filter_add(), where the length of an address (addr_len) is checked only via an assert() statement. Assertions are typically disabled in production builds, meaning that the size check is effectively absent in deployed environments. Consequently, if an attacker supplies an addr_len value larger than the configured maximum (CONFIG_L2FILTER_ADDR_MAXLEN), the subsequent memcpy() operation copies more data than the buffer can hold, causing a classic buffer overflow (CWE-120). This overflow allows an attacker to overwrite adjacent memory, potentially leading to denial of service or arbitrary code execution. The vulnerability affects all RIOT-OS versions up to and including 2025.04. A patch has been committed to address this issue by replacing the assertion with proper input validation. The CVSS 4.0 base score is 6.6, reflecting network attack vector, low attack complexity, no privileges or user interaction required, and high impact on availability. No known exploits are currently reported in the wild. Given RIOT-OS's role in IoT devices, this vulnerability poses a significant risk to embedded systems that rely on it for network filtering functions, especially in environments where untrusted inputs can reach the vulnerable code path.

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #11
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
Docker Security (opens in a new tab)
XML Security (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.1 (opens in a new tab)
V14.1.2 (opens in a new tab)
V13.3.1 (opens in a new tab)
Attack patterns
Buffer Overflow via Environment Variables (opens in a new tab)
Overflow Buffers (opens in a new tab)
Client-side Injection-induced Buffer Overflow (opens in a new tab)
Filter Failure through Buffer Overflow (opens in a new tab)
MIME Conversion (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 18 Jul 2025, 16:01 UTC

WeaknessesCWE-120

Technical details

References

Community reviews

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