# CVE-2017-7562: Auth bypass in krb5

> Remote attackers can impersonate arbitrary principals via a certificate validation flaw in the Kerberos KDC certauth interface.

- **Severity:** Medium 6.5 (`CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Jul 2018
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-vg8p-42hp-9g25, SUSE-SU-2018:1425-1

## What is CVE-2017-7562?

CVE-2017-7562 is a medium-severity authentication bypass vulnerability in Mit Kerberos 5, published on 26 Jul 2018. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

An authentication bypass flaw was found in the way krb5's certauth interface before 1.16.1 handled the validation of client certificates. A remote attacker able to communicate with the KDC could potentially use this flaw to impersonate arbitrary principals under rare and erroneous circumstances.

Weakness: CWE-295 (Improper Certificate Validation), CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2017-7562?

It affects 5 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `krb5` | SUSE:Linux Enterprise Server 12 SP1-LTSS | All versions | 1.12.1-38.5.3 |
| `krb5` | SUSE:Linux Enterprise Server 12-LTSS | All versions | 1.12.1-38.5.3 |
| `krb5` | SUSE:Linux Enterprise Server for SAP Applications 12 SP1 | All versions | 1.12.1-38.5.3 |

Products: Mit Kerberos 5, Redhat Enterprise Linux, Redhat Enterprise Linux Desktop, Redhat Enterprise Linux Server, Redhat Enterprise Linux Workstation.

## How do I fix CVE-2017-7562?

Upgrade to a fixed version.

## Is CVE-2017-7562 being exploited?

There is no known exploitation of CVE-2017-7562 in the wild and no public exploit code.

## Other vulnerabilities in Mit Kerberos 5

- [CVE-2011-0285](https://insights.sbomify.com/CVE-2011-0285/): Use after free in n/a (critical 10.0)
- [CVE-2008-0947](https://insights.sbomify.com/CVE-2008-0947/): Memory corruption in n/a (critical 10.0)
- [CVE-2007-5902](https://insights.sbomify.com/CVE-2007-5902/): Integer overflow in n/a (critical 10.0)
- [CVE-2007-4743](https://insights.sbomify.com/CVE-2007-4743/): Memory corruption in n/a (critical 10.0)
- [CVE-2007-3999](https://insights.sbomify.com/CVE-2007-3999/): Memory corruption in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-7562 and fix it if it is affected.

What it is: CVE-2017-7562 is a medium-severity authentication bypass vulnerability in Mit Kerberos 5, published on 26 Jul 2018. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2017-7562 in the wild and no public exploit code.

Affected product: Mit Kerberos 5. 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-2017-7562/ (Markdown: https://insights.sbomify.com/CVE-2017-7562/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-7562
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-7562
- OSV: https://osv.dev/vulnerability/CVE-2017-7562

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-7562/
Summaries are generated and may contain mistakes; the official description above is the record.