Confluence Server - SSRF (CVE-2021-26072)

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.