# CVE-2026-123746: Symfony: Programmatic Logins Skip the checkPostAuth() Method of User Checkers


- **Severity:** Low 2.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 6 Nov 2026
- **Updated:** 10 Nov 2026
- **Also known as:** DEBIAN-CVE-2026-123746, GHSA-8f57-m8wj-x65w, UBUNTU-CVE-2026-123746

## What is CVE-2026-123746?

CVE-2026-123746 is a low-severity vulnerability in sensiolabs symfony, published on 6 Nov 2026. 

### Official description

The Symfony Security HTTP component AuthenticatorManager::authenticateUser() does not run the firewall user checker’s checkPostAuth() method when a user is authenticated programmatically, allowing an account rejected by a custom user checker, such as an expired account, to be authenticated in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11.

AuthenticatorManager::authenticateUser() is used by UserAuthenticatorInterface::authenticateUser() and by the SecurityBundle’s Security::login() to authenticate a user programmatically, but it does not dispatch the security.authentication.success event, on which checkPostAuth() runs. The fix for CVE-2024-50341 made Security::login() call checkPreAuth(), but checkPostAuth() was still skipped. As a result, an account rejected by a custom user checker in checkPostAuth() is refused by form login and the other authenticators of the firewall, but can still be authenticated programmatically.

Applications are affected when they use a custom user checker that rejects users in checkPostAuth() and authenticate users programmatically, for example after a password reset or an e-mail verification link. A user whose account is rejected can then obtain an authenticated session through that flow. The default user checker does nothing in checkPostAuth(), so the default configuration is not affected.

The fix makes AuthenticatorManager::authenticateUser() dispatch the security.authentication.success event once the token is created and before it is stored, as authentications through the firewall do, so that checkPostAuth() runs and can reject the user.

Weakness: CWE-288 (Authentication Bypass Using an Alternate Path or Channel)

## Which versions are affected by CVE-2026-123746?


## How do I fix CVE-2026-123746?

Upgrade to a fixed version.

## Is CVE-2026-123746 being exploited?

There is no known exploitation of CVE-2026-123746 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123746 and fix it if it is affected.

What it is: CVE-2026-123746 is a low-severity vulnerability in sensiolabs symfony, published on 6 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123746 in the wild and no public exploit code.

Affected product: sensiolabs symfony. 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-2026-123746/ (Markdown: https://insights.sbomify.com/CVE-2026-123746/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123746
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123746
- OSV: https://osv.dev/vulnerability/CVE-2026-123746

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123746/
Summaries are generated and may contain mistakes; the official description above is the record.