Cap-go Capgo Upload Proxy upload.ts builder_job_id unrestricted upload

Summaryinfo

A vulnerability labeled as critical has been found in Cap-go Capgo. This vulnerability affects unknown code of the file supabase/functions/_backend/public/build/upload.ts of the component Upload Proxy. Executing a manipulation of the argument builder_job_id can lead to unrestricted upload. The identification of this vulnerability is CVE-2026-100625. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical was found in Cap-go Capgo (the affected version unknown). This vulnerability affects an unknown part of the file supabase/functions/_backend/public/build/upload.ts of the component Upload Proxy. The manipulation of the argument builder_job_id with an unknown input leads to a unrestricted upload vulnerability. The CWE definition for the vulnerability is CWE-434. The product allows the attacker to upload or transfer files of dangerous types that can be automatically processed within the product's environment. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-100625 since 09/26/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/26/2026). The MITRE ATT&CK project declares the attack technique as T1608.002.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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• Cap-go

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• Capgo

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