What’s Vulnerable › Vulnerabilities

CVE-2026-56331: Capgo - Improper Error Handling in Accept Invitation Endpoint via Invalid Magic String

• Severity: medium (CVSS 5.3 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: 2026-06-30 · updated 2026-07-01
• Weakness: CWE-209

Description

Capgo before 12.128.2 contains improper error handling in the /private/accept_invitation endpoint that returns HTTP 500 instead of safe 4xx errors when magic_invite_string is invalid. Attackers can trigger this vulnerability using only the public key by submitting malformed magic_invite_string values to cause server errors and leak internal processing details.

Affected products

• Capgo: before 12.128.2 — fixed in 12.128.2

How to fix

Upgrade to a fixed version: Capgo 12.128.2. Check the vendor advisory for mitigations.

References

• https://github.com/Cap-go/capgo/security/advisories/GHSA-34p8-fh3m-376x
• https://www.vulncheck.com/advisories/capgo-improper-error-handling-in-accept-invitation-endpoint-via-invalid-magic-string
• https://github.com/Cap-go/capgo/security/advisories/GHSA-34p8-fh3m-376x

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