CVE-2021-21377
CWE-601Published: March 23, 2021· Updated: Jun 17, 2026
Official Description
OMERO.web is open source Django-based software for managing microscopy imaging. OMERO.web before version 5.9.0 supports redirection to a given URL after performing login or switching the group context. These URLs are not validated, allowing redirection to untrusted sites. OMERO.web 5.9.0 adds URL validation before redirecting. External URLs are not considered valid, unless specified in the omero.web.redirect_allowed_hosts setting.
Technical Analysis
CVE-2021-21377 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
Official Patches & Advisories
All References (10)
Quick Facts
Related CVEs (CWE-601)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-21377 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts