# CVE-2026-25222: PolarLearn Affected by User Enumeration via Argon2 Timing Attack on Sign-In Endpoint

> Unauthenticated attackers can enumerate registered users by timing login responses, revealing valid email addresses on the PolarLearn platform.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:L/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:** 2 Feb 2026
- **Updated:** 4 Feb 2026
- **Also known as:** GHSA-wcr9-mvr9-4qh5

## What is CVE-2026-25222?

CVE-2026-25222 is a medium-severity vulnerability in polarnl PolarLearn, published on 2 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

PolarLearn is a free and open-source learning program. In 0-PRERELEASE-15 and earlier, a timing attack vulnerability in the sign-in process allows unauthenticated attackers to determine if a specific email address is registered on the platform. By measuring the response time of the login endpoint, an attacker can distinguish between valid and invalid email addresses. This occurs because the server only performs the computationally expensive Argon2 password hashing if the user exists in the database. Requests for existing users take significantly longer (~650ms) than requests for non-existent users (~160ms).

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2026-25222?

It affects 1 product.


Products: Polarlearn Polarlearn.

## How do I fix CVE-2026-25222?

No fix has been published for CVE-2026-25222 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-25222 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-25222 exists.

## Other vulnerabilities in polarnl PolarLearn

- [CVE-2026-25885](https://insights.sbomify.com/CVE-2026-25885/): PolarLearn allows Unauthenticated WebSocket access allows subscribing to and posting in arbitrary group chats (critical 10.0)
- [CVE-2026-39322](https://insights.sbomify.com/CVE-2026-39322/): PolarLearn: Any password authenticates banned accounts and grants API access (critical 9.2)
- [CVE-2026-35610](https://insights.sbomify.com/CVE-2026-35610/): PolarLearn has a Server Action Admin Bypass in Account Management Actions (high 8.8)
- [CVE-2026-25126](https://insights.sbomify.com/CVE-2026-25126/): PolarLearn's unvalidated vote direction allows vote count manipulation (high 7.1)
- [CVE-2026-25221](https://insights.sbomify.com/CVE-2026-25221/): PolarLearn has Multiple Login CSRFs via Missing OAuth state Parameter (GitHub & Google) (low 2.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-25222 and fix it if it is affected.

What it is: CVE-2026-25222 is a medium-severity vulnerability in polarnl PolarLearn, published on 2 Feb 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-2026-25222 exists.

Affected product: polarnl PolarLearn. 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-2026-25222/ (Markdown: https://insights.sbomify.com/CVE-2026-25222/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-25222
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-25222
- OSV: https://osv.dev/vulnerability/CVE-2026-25222

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-25222/
Summaries are generated and may contain mistakes; the official description above is the record.