Is CVE-2021-21377 in the CISA KEV catalog?

No. CVE-2021-21377 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-21377?

CVE-2021-21377 has a CVSS v3 base score of 4.8 (MEDIUM).

What is the EPSS score for CVE-2021-21377?

CVE-2021-21377 has an EPSS score of 0.83% (53th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-21377?

Upgrade omero.web to 5.9.0 or later.

CVE & CISA-KEV Catalog

CVE-2021-21377

MEDIUM

4.8

CVSS v3

NVD

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.

CWE-601Open Redirect

How to fix

Remediation Available

omero.webNVD

Affected:< 5.9.0Fixed in:5.9.0CVE-2021-21377derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredLow

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N

Exploit Intelligence

0.83%probability of exploitation in 30 days

53rdpercentile

Moderate risk: more likely to be exploited than 53% of all known CVEs.

References

Patch1

github.com

Vendor Advisory1

openmicroscopy.org

Third-Party Advisory3

Related Vulnerabilities

Other CWE-601 (Open Redirect) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-4123	High	7.6	98%	-	Fix
CVE-2018-11784	Medium	4.3	94%	-	Fix
CVE-2021-22881	Medium	6.1	87%	-	Fix
CVE-2022-45402	Medium	6.1	82%	-	Fix
CVE-2017-1000117	High	8.8	78%	-	Fix
CVE-2019-10098	Medium	6.1	74%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.