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CVE-2026-56316 Cap-go CVE debrief

CVE-2026-56316 is a medium-severity information disclosure vulnerability in Cap-go versions before 12.128.2. The vulnerability exists in the OPTIONS /build/upload/:jobId/* endpoint, allowing unauthenticated attackers to enumerate valid builder job IDs through observable response discrepancies. This issue has a CVSS score of 6.9. The vulnerability was published on June 21, 2026. Affected users should review and update their installations to mitigate potential risks.

Vendor
Cap-go
Product
capgo
CVSS
MEDIUM 6.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-21
Original CVE updated
2026-06-24
Advisory published
2026-06-21
Advisory updated
2026-06-24

Who should care

Users of Cap-go versions before 12.128.2 should be aware of this vulnerability and take necessary actions to secure their installations. This includes reviewing the endpoint configurations and ensuring that the system is updated to the latest version. Security teams and administrators responsible for maintaining Cap-go installations should prioritize this vulnerability and plan for mitigation.

Technical summary

The vulnerability is located in the OPTIONS /build/upload/:jobId/* endpoint of Cap-go. An unauthenticated attacker can probe this endpoint to distinguish between valid and invalid job IDs, leading to potential enumeration of valid job IDs. This could result in sustained unauthenticated traffic for resource consumption. The CVSS vector for this vulnerability is CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/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.

Defensive priority

Medium priority due to potential for resource consumption and information disclosure through enumeration.

Recommended defensive actions

  • Update Cap-go to version 12.128.2 or later
  • Review and restrict access to the OPTIONS /build/upload/:jobId/* endpoint
  • Monitor for unusual traffic patterns that could indicate exploitation attempts
  • Implement rate limiting on the affected endpoint
  • Verify the system's current version and configuration

Evidence notes

The primary evidence for this vulnerability comes from the CVE record and the NVD detail page. The vulnerability affects Cap-go versions before 12.128.2. The endpoint in question allows unauthenticated attackers to probe for valid job IDs. Users should verify their current version of Cap-go and review the endpoint configurations to ensure they are not exposed.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-56316 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-56316

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-56316 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-56316

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.