CVE-2026-56331

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.

CVSS v3.1 Score

5.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS — Exploit Prediction

0.0025

Probability of exploitation

0.16%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-209 CWE-209

References

Other 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

Frequently Asked Questions

What is CVE-2026-56331? +

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. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-56331? +

CVE-2026-56331 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0025, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-56331? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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