# CVE-2021-40856: Auerswald COMfortel - Path Traversal

> Live exploitation tracking for CVE-2021-40856 by the CrowdSec Live Exploit Tracker, built from real-world attack data crowdsourced from CrowdSec's global network.

Page: https://tracker.crowdsec.net/cves/CVE-2021-40856

## Key facts

- **Exploitation phase:** Limited Exploitation. The vulnerability is known but shows very limited attacker interest or exploitation activity.
- **CVSS score:** 7.5
- **Public exploit available:** Yes
- **Affected products:** Auerswald COMfortel 1400 IP, Auerswald COMfortel 2600 IP
- **Weaknesses:** CWE-706 (Use of Incorrectly-Resolved Name or Reference)
- **Tags:** iot

## Description

Auerswald COMfortel 1400 IP and 2600 IP before 2.8G devices allow Authentication Bypass via the /about/../ substring.

## CrowdSec analysis

[CVE-2021-40856](https://euvd.enisa.europa.eu/vulnerability/CVE-2021-40856) is a vulnerability affecting Auerswald COMfortel IP devices, where improper path handling enables authentication bypass through certain crafted requests.

CrowdSec has been tracking this vulnerability and its exploits since 1st of June 2025.

Insights from the CrowdSec network reveal that the attackers trying to exploit CVE-2021-40856 are composed of a fairly even mix of opportunistic and targeted actors. Some attackers employ preliminary reconnaissance, while others use indiscriminate scanning.
Data from the CrowdSec community also indicates a gradual decrease in attacks targeting CVE-2021-40856. While still present in the wild, exploitation levels have dropped noticeably week-over-week. This may signal that the vulnerability is becoming less relevant or that defenses are improving fast enough for attackers to lose interest.

Observed exploitation attempts typically target URLs containing `/about/..` combined with specific request patterns.

## Timeline

- 2021-12-13: CVE Published. CVE-2021-40856 is published to NVD.
- 2025-06-01: Rule Released. CrowdSec releases a rule to detect CVE-2021-40856 exploitation attempts against the CrowdSec Network.
- 2025-06-05: CrowdSec First Seen. CrowdSec observes in-the-wild exploitation of CVE-2021-40856 for the first time.

## References

- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-40856.yaml

## Live exploitation data

The [Live Exploit Tracker page](https://tracker.crowdsec.net/cves/CVE-2021-40856) follows observed exploitation activity for CVE-2021-40856. [Request an API key](https://tracker.crowdsec.net/request-api-key) for full access to its exploitation timeline, attacking IP addresses and blocklists.