# CVE-2026-45274: MyBooks: Unauthenticated Registration Bypass via Missing Server-Side ALLOW_REGISTER Enforcement

> Attackers can bypass registration restrictions to create accounts and gain unauthorized access to user-level features in MyBooks.

- **Severity:** Medium 6.9 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** GHSA-3q85-5vj5-qx5v

## What is CVE-2026-45274?

CVE-2026-45274 is a medium-severity missing authorization vulnerability in PoxenStudio talebook, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-602 (Client-Side Enforcement of Server-Side Security)

## Which versions are affected by CVE-2026-45274?


## How do I fix CVE-2026-45274?

No fix has been published for CVE-2026-45274 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-45274 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45274 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45274 and fix it if it is affected.

What it is: CVE-2026-45274 is a medium-severity missing authorization vulnerability in PoxenStudio talebook, published on 19 Aug 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-2026-45274 exists.

Affected product: PoxenStudio talebook. 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-2026-45274/ (Markdown: https://insights.sbomify.com/CVE-2026-45274/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45274
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45274
- OSV: https://osv.dev/vulnerability/CVE-2026-45274

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45274/
Summaries are generated and may contain mistakes; the official description above is the record.