CVE-2026-55163 is a medium-severity (CVSS 6.3) CWE-863 vulnerability in lemur. A fix is available for lemur — see the affected versions and patch details below.
Lemur: Privilege escalation via PUT /api/1/roles/<id> — non-admin role members can rewrite role membership
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-55163.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-55163 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
lemurReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Lemur manages TLS certificate creation. Prior to 1.9.2, PUT /api/1/roles/ in lemur/roles/views.py:298 authorized updates with RoleMemberPermission(role_id), which allowed either an administrator or any existing member of the target role. The handler passed data["users"] and data["name"] to service.update, allowing a non-admin member to add or remove other users and rename the role. This enabled lateral privilege grants within roles that control certificate and authority access and could deny access by removing legitimate members. The DELETE handler already required admin_permission, confirming that the weaker PUT authorization was inconsistent. The fix applies the same administrator-only requirement to the PUT handler. This issue is fixed in version 1.9.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | lemur | all versions | 1.9.2pip install --upgrade 'lemur==1.9.2' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for lemur, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update lemur to 1.9.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55163 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-55163 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-55163. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-55163 in your dependencies?
O3 Security finds CVE-2026-55163 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.