CVE-2026-19670 Incorrect Authorization in CISA Malcolm
Authenticated low-privilege users can bypass RBAC restrictions and access admin-only endpoints by using percent-encoded URIs in CISA Malcolm.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-19670?
CVE-2026-19670 is a medium-severity authentication bypass vulnerability in CISAgov Malcolm, published on 18 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Malcolm's nginx Lua role-based access control (RBAC) layer decides whether an authenticated user may reach a role-restricted path (e.g. /htadmin, /auth, /admin_login, /arkime/api/esadmin, NetBox, upload endpoints) by pattern-matching the raw, percent-encoded request URI. Nginx itself, however, selects which location block actually serves the request using the percent-decoded, normalized URI. Because the RBAC check never percent-decodes its input, an authenticated low-privilege user can request an admin-only path using percent-encoding (e.g. /%68tadmin.php) and have nginx route it to the restricted location while the Lua RBAC gate evaluating the un-decoded raw string finds no matching restriction and grants access.
Weakness: CWE-863
Which versions are affected by CVE-2026-19670?
How do I fix CVE-2026-19670?
No fix has been published for CVE-2026-19670 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-19670 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-19670 exists.
Sources
Also known as GHSA-4887-2gc3-6j9r.