Skip to content
Fencer Intel
medium 4.8

CVE-2021-21377 json

Open Redirect in OMERO.web

published 5y ago modified 4mo ago also GHSA-g4rf-pc26-6hmr , PYSEC-2021-32 , EUVD-2021-0158

cvss
4.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi omero-web 5.9.0
  • openmicroscopy omero.web 5.9.0

Is CVE-2021-21377 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Exploit prediction

0.83% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.9 AV:N/AC:M/Au:S/C:P/I:P/A:N
GitHub 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
pypi omero-web
<5.9.0
5.9.0

Affected products

  • ome omero-web

Classification

Weakness
  • CWE-601 URL Redirection to Untrusted Site

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.