What’s Vulnerable › Vulnerabilities

CVE-2026-56280: Cap-go - Privilege Inversion in Build Log Stream via SSE Disconnect

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-22 · updated 2026-10-25
• Weakness: CWE-862

Description

Cap-go before 12.128.2 contains a privilege inversion vulnerability in GET /build/logs/:jobId that allows read-only API key holders to cancel running native builds. The endpoint registers an abort listener on the SSE stream that unconditionally invokes cancelBuildOnDisconnect() using the privileged server-side BUILDER_API_KEY when clients disconnect, bypassing the app.build_native permission check required by the explicit POST /build/cancel/:jobId endpoint. Attackers with read-only API keys can repeatedly disrupt native build operations and CI/CD workflows by opening the log stream and dropping the connection.

Affected products

• Cap-go capgo: before 12.128.2 — fixed in 12.128.2

How to fix

Upgrade to a fixed version: Cap-go capgo 12.128.2. Check the vendor advisory for mitigations.

References

• https://github.com/Cap-go/capgo/security/advisories/GHSA-95g7-xwwx-j737
• https://www.vulncheck.com/advisories/cap-go-privilege-inversion-in-build-log-stream-via-sse-disconnect
• https://github.com/Cap-go/capgo/security/advisories/GHSA-95g7-xwwx-j737

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