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19Track

Malcolm Vulnerable to Authorization Bypass via URI Normalization Differential in Nginx Lua RBAC

cisagov Malcolm · CVE-2026-63177
0 news outlets0 CERTs and agencies0 research labs

Assessment: Track

SSVC decision points: exploitation none, automatable no, technical impact partial, deployment low.

What is it?

Malcolm is a network traffic analysis tool suite. Prior to version 26.07.0, role-based access control enforced in the Nginx OpenResty Lua layer evaluates the raw, unnormalized `ngx.var.request_uri`, while Nginx itself routes requests using the normalized path. An authenticated low-privilege user can prepend a traversal segment (for example `/x/../upload/...`) so that Nginx routes the request to a restricted backend while the Lua role check fails to match any rule and falls open, granting access it should deny. Version 26.07.0 fixes the issue.

Evidence

No coverage recorded yet.

Exploitation

  • Exploit code published (not verified by us)
  • Exploited in the wild (confirmed by a source)
  • Listed as known exploited (CISA KEV)
CVSS
7.1
EPSS
–
First seen
18 Aug 2026
Status
corroborated

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