Description
Capgo (capgo.app) exposes a native build TUS upload proxy (supabase/functions/_backend/public/build/upload.ts) that authorizes a caller against a single build job identified by the supplied builder_job_id and validates only that job's stored upload_path, but then forwards the user-controlled TUS resource suffix taken from /build/upload/:jobId/* to the builder service while injecting Capgo's privileged builder API key. Because the forwarded suffix is never bound to the authorized job's upload_path or upload_session_key, a caller holding a valid 'all' or 'write' Capgo API key with app.build_native permission for one application can use its authorized proxy path for job A to write to the TUS upload resource of another job B, provided that resource suffix is known or exposed, corrupting that build's artifacts. All versions are affected; no patch was available at the time of advisory publication.
References3
Metrics
- CVSS 3.1
-
7.1
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:H/A:L - CVSS 4.0
-
8.7
HIGH
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 23 · as of 9 November 2026
- CWE
- CWE-441
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.