# CVE-2021-28373: Auth bypass in n/a

> An authentication bypass in Tiny Tiny RSS allows attackers to log in using only an OTP code, bypassing password validation.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:** No
- **Published:** 13 Mar 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-vv4w-hr59-hmw6

## What is CVE-2021-28373?

CVE-2021-28373 is a high-severity authentication bypass vulnerability in n/a, published on 13 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The auth_internal plugin in Tiny Tiny RSS (aka tt-rss) before 2021-03-12 allows an attacker to log in via the OTP code without a valid password. NOTE: this issue only affected the git master branch for a short time. However, all end users are explicitly directed to use the git master branch in production. Semantic version numbers such as 21.03 appear to exist, but are automatically generated from the year and month. They are not releases.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2021-28373?

It affects 1 product.


Products: Tt-Rss Tiny Tiny Rss.

## How do I fix CVE-2021-28373?

No fix has been published for CVE-2021-28373 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-28373 being exploited?

There is no known exploitation of CVE-2021-28373 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2020-25787](https://insights.sbomify.com/CVE-2020-25787/): Server-side request forgery in n/a (critical 9.8)
- [CVE-2017-16896](https://insights.sbomify.com/CVE-2017-16896/): SQL injection in n/a (critical 9.8)
- [CVE-2020-25788](https://insights.sbomify.com/CVE-2020-25788/): Cross-site scripting in n/a (high 8.1)
- [CVE-2020-25789](https://insights.sbomify.com/CVE-2020-25789/): Cross-site scripting in n/a (medium 6.1)
- [CVE-2017-1000035](https://insights.sbomify.com/CVE-2017-1000035/): Cross-site scripting in n/a (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28373 and fix it if it is affected.

What it is: CVE-2021-28373 is a high-severity authentication bypass vulnerability in n/a, published on 13 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-28373 in the wild and no public exploit code.

Affected product: n/a. 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-2021-28373/ (Markdown: https://insights.sbomify.com/CVE-2021-28373/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28373
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28373
- OSV: https://osv.dev/vulnerability/CVE-2021-28373

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28373/
Summaries are generated and may contain mistakes; the official description above is the record.