Lemur has an authorization bypass in StrictRolePermission / AuthorityCreatorPermission

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.8 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-48508: 0.33% estimated exploitation activity in the next 30 days; percentile 26.10 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary StrictRolePermission and AuthorityCreatorPermission in lemur/auth/permissions.py call flaskprincipal.Permission.init() with zero Needs when their config flags are unset. Both flags defaulted to False in code prior to the fix, so this was the state of any Lemur install that hadn't explicitly opted in. Flask-Principal's Permission.allows() returns True whenever self.needs is empty. The .can() gate therefore passes for every authenticated identity, including the lowest-privilege role Lemur ships (read-only). A user holding only read-only can create root Certificate Authorities, create and edit notifications (an SSRF sink), create domain entries, and upload arbitrary certificates. These classes are the sole authorization check on those endpoints. Root Cause flaskprincipal.Permission.allows() (upstream, v0.4.0): When self.needs == set(), the first guard is falsy and is skipped. excludes is also empty, so allows() returns True for any identity. AuthenticatedResource (the parent…

Published by the source

25 Jun 2026, 18:48 UTC

Last modified by the source

13 Jul 2026, 16:42 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-qcqw-jwxc-2hqg

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-qcqw-jwxc-2hqg

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# Patch Next advisory brief: CVE-2026-48508

Advisory: Lemur has an authorization bypass in StrictRolePermission / AuthorityCreatorPermission
IDs: CVE-2026-48508, GHSA-qcqw-jwxc-2hqg
Record: https://patchnext.com/advisories/cve-2026-48508 (revision 2, source checked 26 Oct 2026, 13:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: lemur 1.9.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI lemur: affected <= 1.9.0; fixed in 1.9.1

## Suggested inspection (read-only)
- `python -m pip show lemur`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on lemur.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-qcqw-jwxc-2hqg (OSV record GHSA-qcqw-jwxc-2hqg lists affected ranges: PyPI lemur >=0 <1.9.1 (fixed))
- Verified: https://github.com/advisories/GHSA-qcqw-jwxc-2hqg (GitHub-reviewed advisory GHSA-qcqw-jwxc-2hqg lists affected ranges: PyPI lemur >=0 <=1.9.0)

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