Summary
Background
OMERO.web loads various information about the current user such as their id, name and the groups they are in, and these are available on the main webclient pages. Some additional information being loaded is not used by the webclient and is being removed in this release.
Workarounds
No workaround
References
For more information
If you have any questions or comments about this advisory:
Impact
OMERO.web before 5.9.0
CVE-2021-21376 has a CVSS score of 6.4 (High). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.9.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
5.9.0
Frequently Asked Questions
- What is CVE-2021-21376? CVE-2021-21376 is a high-severity security vulnerability in omero-web (pip), affecting versions < 5.9.0. It is fixed in 5.9.0.
- How severe is CVE-2021-21376? CVE-2021-21376 has a CVSS score of 6.4 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of omero-web are affected by CVE-2021-21376? omero-web (pip) versions < 5.9.0 is affected.
- Is there a fix for CVE-2021-21376? Yes. CVE-2021-21376 is fixed in 5.9.0. Upgrade to this version or later.
- Is CVE-2021-21376 exploitable, and should I be worried? Whether CVE-2021-21376 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2021-21376 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2021-21376? Upgrade
omero-webto 5.9.0 or later.