# CVE-2019-19521: Auth bypass in n/a

> Attackers can bypass authentication in OpenBSD services like smtpd and ldapd by using the -schallenge username due to a flaw in libc.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Dec 2019
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-gw7q-976q-g767

## What is CVE-2019-19521?

CVE-2019-19521 is a critical authentication bypass vulnerability in Openbsd Openbsd, published on 4 Dec 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libc in OpenBSD 6.6 allows authentication bypass via the -schallenge username, as demonstrated by smtpd, ldapd, or radiusd. This is related to gen/auth_subr.c and gen/authenticate.c in libc (and login/login.c and xenocara/app/xenodm/greeter/verify.c).

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2019-19521?

It affects 1 product.


Products: Openbsd Openbsd.

## How do I fix CVE-2019-19521?

No fix has been published for CVE-2019-19521 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-19521 being exploited?

There is no known exploitation of CVE-2019-19521 in the wild and no public exploit code.

## Other vulnerabilities in Openbsd Openbsd

- [CVE-2007-1365](https://insights.sbomify.com/CVE-2007-1365/): Memory corruption in n/a (critical 10.0)
- [CVE-2004-0220](https://insights.sbomify.com/CVE-2004-0220/): Integer overflow in n/a (critical 10.0)
- [CVE-2004-0083](https://insights.sbomify.com/CVE-2004-0083/): Memory corruption in n/a (critical 10.0)
- [CVE-2004-0084](https://insights.sbomify.com/CVE-2004-0084/): Memory corruption in n/a (critical 10.0)
- [CVE-2001-0284](https://insights.sbomify.com/CVE-2001-0284/): Memory corruption in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-19521 and fix it if it is affected.

What it is: CVE-2019-19521 is a critical authentication bypass vulnerability in Openbsd Openbsd, published on 4 Dec 2019. 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-2019-19521 in the wild and no public exploit code.

Affected product: Openbsd Openbsd. 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-2019-19521/ (Markdown: https://insights.sbomify.com/CVE-2019-19521/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-19521
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-19521
- OSV: https://osv.dev/vulnerability/CVE-2019-19521

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-19521/
Summaries are generated and may contain mistakes; the official description above is the record.