CVE-2021-21377Network attack vector

User redirection via unvalidated destination URL

Published Mar 23, 2021 · Updated Aug 3, 2024

Open redirect in OMERO.web before 5.9.0 allows remote authenticated users to redirect browsers to untrusted sites after login or a group switch. The WebclientLoginView.handle_logged_in and change_active_group paths passed the request-controlled url value directly to HttpResponseRedirect without checking the destination host. Exploitation requires a valid account and user interaction; the bounded result is navigation to an attacker-chosen site, enabling phishing or credential capture by that external site.

CVSS severity4.8
Medium
EPSS probability0.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in OMERO.web before 5.9.0 allows remote authenticated users to redirect browsers to untrusted sites after login or a group switch. The WebclientLoginView.handle_logged_in and change_active_group paths passed the request-controlled url value directly to HttpResponseRedirect without checking the destination host. Exploitation requires a valid account and user interaction; the bounded result is navigation to an attacker-chosen site, enabling phishing or credential capture by that external site.

The record

CVE
CVE-2021-21377
Published
Mar 23, 2021
Updated
Aug 3, 2024
Vendor
Open Microscopy Environment
Product
OMERO.web
Classifications
CWE-601, T1566.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 5.9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Open Microscopy Environment · OMERO.webversion=< 5.9.0

Published CVSS scores

4.8GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
4.9NIST NVDAV:N/AC:M/Au:S/C:P/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site ('Open Redirect')
T1566.002Phishing: Spearphishing Link

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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