CVE-2026-63177

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.

CVSS 4.0

7.1CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS 3.1

7.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

EPSS

0.4% chance of exploitation in the next 30 days; higher than 30% of CVEs (scores of 2026-10-25)

CWE

CWE-863

Published

2026-08-11

Modified

2026-10-24

Record from

the NVD, synced 2026-10-24

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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