What’s Vulnerable › Vulnerabilities

CVE-2026-63177: Malcolm Vulnerable to Authorization Bypass via URI Normalization Differential in Nginx Lua RBAC

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-11 · updated 2026-10-24
• Weakness: CWE-863

Description

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.

Affected products

• cisagov Malcolm: before 26.07.0

References

• https://github.com/cisagov/CSAF/blob/develop/csaf_files/OT/white/2026/icsa-26-230-01.json
• https://github.com/cisagov/Malcolm/releases/tag/v26.07.0
• https://github.com/cisagov/Malcolm/security/advisories/GHSA-m5fr-rv3h-xg2r
• https://www.cisa.gov/news-events/ics-advisories/icsa-26-230-01

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