# CVE-2026-92289: Lemonldap::NG::Portal versions from 2.23.0 before 2.23.4 for Perl allow a PKCE bypass for public Relying Parties in "PKCE or secret" mode be

> Attackers can bypass PKCE protections in LemonLDAP::NG Portal to exchange intercepted authorization codes for user tokens, leading to account takeover.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Sep 2026
- **Updated:** 26 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-92289, GHSA-vw4x-93xp-f6f3, UBUNTU-CVE-2026-92289

## What is CVE-2026-92289?

CVE-2026-92289 is a critical authentication bypass vulnerability, published on 25 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Lemonldap::NG::Portal versions from 2.23.0 before 2.23.4 for Perl allow a PKCE bypass for public Relying Parties in "PKCE or secret" mode because checkEndPointAuthenticationCredentials does not verify the client secret.

With oidcRPMetaDataOptionsRequirePKCE set to 2, the authorization endpoint issues a code even when the request carries no code_challenge, and token() admits the exchange as long as a challenge was stored or an authentication method was returned for the caller. checkEndPointAuthenticationCredentials() skips the secret comparison for a Relying Party marked public and still returns the method deduced from the request, so any Basic or form credential satisfies the secret branch. validatePKCEChallenge() then passes, because neither a challenge nor a verifier is present.

An attacker who intercepts an authorization code issued to a public Relying Party can exchange it for the user's access, ID and refresh tokens by replaying the client_id with an arbitrary secret, which is the attack PKCE prevents. Dynamic client registration creates every Relying Party in this mode.

Weakness: CWE-1390 (Weak Authentication)

## Which versions are affected by CVE-2026-92289?


## How do I fix CVE-2026-92289?

Upgrade to a fixed version.

## Is CVE-2026-92289 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-92289 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-92289 and fix it if it is affected.

What it is: CVE-2026-92289 is a critical authentication bypass vulnerability, published on 25 Sep 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-2026-92289 exists.

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-2026-92289/ (Markdown: https://insights.sbomify.com/CVE-2026-92289/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-92289
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-92289
- OSV: https://osv.dev/vulnerability/CVE-2026-92289

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-92289/
Summaries are generated and may contain mistakes; the official description above is the record.