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Security advisory

Type: advisorySources: OSVCVE: CVE-2021-21377

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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2021-21377
Confirmed fixed CVEs
Not specified
Updated in this feed
31 Oct 2026, 11:32 UTC · Revision 1

Source evidence

CVE-2021-21377

core-osv · Original source

Published 23 Mar 2021, 16:15 UTC

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.

osv:CVE-2021-21377
Complete source record
{
  "id": "67467c571cba19624e858d5dc3760002a8b983665a8788b9f285433c26da5153",
  "url": "https://osv.dev/vulnerability/CVE-2021-21377",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-21377",
    "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.",
    "evidence": "osv:CVE-2021-21377",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-21377",
      "aliases": [
        "CVE-2021-21377",
        "GHSA-g4rf-pc26-6hmr",
        "PYSEC-2021-32"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/ome/omero-web",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1303ae337622820b5eacb3967f236ec113e32ef1"
                },
                {
                  "fixed": "952f8e5d28532fbb14fb665982211329d137908c"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:openmicroscopy:omero.web:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "5.9.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "952f8e5d28532fbb14fb665982211329d137908c"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v5.8.1",
            "v5.8.0",
            "v5.7.1",
            "v5.7.0",
            "v5.6.3",
            "v5.6.2",
            "v5.6.1",
            "v5.6.0",
            "v5.6.dev7",
            "v5.6.dev6",
            "v5.6.dev5",
            "v5.6.dev4",
            "v5.6.dev3",
            "v5.6.dev2",
            "v5.6.dev1",
            "v5.5.dev2",
            "v5.5.dev1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-21377.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:29.623641762Z",
      "provider": "osv",
      "references": [
        "https://github.com/ome/omero-web/blob/master/CHANGELOG.md#590-march-2021",
        "https://github.com/ome/omero-web/security/advisories/GHSA-g4rf-pc26-6hmr",
        "https://pypi.org/project/omero-web/",
        "https://www.openmicroscopy.org/security/advisories/2021-SV2/",
        "https://github.com/ome/omero-web/commit/952f8e5d28532fbb14fb665982211329d137908c"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-21377",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 385454,
  "published_at": "2021-03-23T16:15:14.283+00:00"
}