# CVE-2021-26072: Confluence Server - SSRF

> Live exploitation tracking for CVE-2021-26072 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-2021-26072

## Key facts

- **Exploitation phase:** Limited Exploitation. The vulnerability is known but shows very limited attacker interest or exploitation activity.
- **CVSS score:** 4.3
- **Public exploit available:** Yes
- **Affected products:** Atlassian Confluence Server, Atlassian Confluence Data Center
- **Weaknesses:** CWE-918 (Server-Side Request Forgery (SSRF))
- **Tags:** enterprise_software, wiki

## Description

The WidgetConnector plugin in Confluence Server and Confluence Data Center before version 5.8.6 allowed remote attackers to manipulate the content of internal network resources via a blind Server-Side Request Forgery (SSRF) vulnerability.

## CrowdSec analysis

[CVE-2021-26072](https://euvd.enisa.europa.eu/vulnerability/CVE-2021-26072) is a vulnerability in the WidgetConnector plugin for Atlassian Confluence Server and Data Center prior to version 5.8.6, which allows remote attackers to exploit a blind Server-Side Request Forgery (SSRF) flaw. This vulnerability could enable attackers to manipulate or access internal network resources, potentially leading to unauthorized information disclosure or further attacks within the internal network.

CrowdSec has been tracking this vulnerability and its exploits since 29th of October 2025.

CrowdSec network observations suggest that most exploitation of CVE-2021-26072 involves focused reconnaissance to identify viable targets. Attackers typically tailor their campaigns based on system exposure and configuration. It is unlikely that a given attack is accidental.
Data from the CrowdSec community also indicates a gradual decrease in attacks targeting CVE-2021-26072. 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.

Attackers exploit this vulnerability by sending requests to the `/rest/sharelinks/1.0/link` endpoint with a crafted `url` parameter, enabling server-side request forgery to arbitrary external or internal resources.

## Timeline

- 2021-04-01: CVE Published. CVE-2021-26072 is published to NVD.
- 2025-10-29: Rule Released. CrowdSec releases a rule to detect CVE-2021-26072 exploitation attempts against the CrowdSec Network.
- 2025-11-05: CrowdSec First Seen. CrowdSec observes in-the-wild exploitation of CVE-2021-26072 for the first time.

## References

- https://jira.atlassian.com/browse/CONFSERVER-61399
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-26072.yaml

## Live exploitation data

The [Live Exploit Tracker page](https://tracker.crowdsec.net/cves/CVE-2021-26072) follows observed exploitation activity for CVE-2021-26072. [Request an API key](https://tracker.crowdsec.net/request-api-key) for full access to its exploitation timeline, attacking IP addresses and blocklists.