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

> Attackers can trigger server errors on the invitation endpoint to leak internal processing details via improper error handling.

- **Severity:** Medium 6.9 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Jun 2026
- **Updated:** 1 Jul 2026
- **Also known as:** GHSA-34p8-fh3m-376x, GHSA-994r-m5r3-f3p9

## What is CVE-2026-56331?

CVE-2026-56331 is a medium-severity vulnerability in Capgo, published on 30 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-209 (Generation of Error Message Containing Sensitive Information)

## Which versions are affected by CVE-2026-56331?


## How do I fix CVE-2026-56331?

No fix has been published for CVE-2026-56331 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-56331 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-56331 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56331 and fix it if it is affected.

What it is: CVE-2026-56331 is a medium-severity vulnerability in Capgo, published on 30 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-56331 exists.

Affected product: Capgo. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-56331/ (Markdown: https://insights.sbomify.com/CVE-2026-56331/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56331
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56331
- OSV: https://osv.dev/vulnerability/CVE-2026-56331

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56331/
Summaries are generated and may contain mistakes; the official description above is the record.