# CVE-2020-27846: XML Processing error in github.com/crewjam/saml

> Attackers can bypass SAML authentication in the crewjam/saml library due to signature verification flaws, compromising confidentiality, integrity, and availability.

- **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:** Yes
- **Published:** 21 Dec 2020
- **Updated:** 4 Aug 2024
- **Also known as:** BIT-grafana-2020-27846, GHSA-4hq8-gmxx-h6w9, GO-2021-0058

## What is CVE-2020-27846?

CVE-2020-27846 is a critical authentication bypass vulnerability in Fedoraproject Fedora, published on 21 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A signature verification vulnerability exists in crewjam/saml. This flaw allows an attacker to bypass SAML Authentication. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Weakness: CWE-115 (Misinterpretation of Input)

## Which versions are affected by CVE-2020-27846?

4 open source packages ship an affected version, including github.com/crewjam/saml and grafana. It affects 6 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/crewjam/saml` | Go | All versions | 0.4.3 |
| `github.com/crewjam/saml` | Go | All versions | 0.4.3 |
| `github.com/crewjam/saml` | Go | All versions | 0.4.3 |
| `grafana` | Bitnami | All versions | 6.7.5, 7.2.3, 7.3.6 |

Products: Fedoraproject Fedora, Grafana Grafana, Redhat Enterprise Linux, Redhat Openshift Container Platform, Redhat Openshift Service Mesh, Saml Project Saml.

## How do I fix CVE-2020-27846?

Upgrade github.com/crewjam/saml to 0.4.3 or later.

## Is CVE-2020-27846 being exploited?

There is no known exploitation of CVE-2020-27846 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-27846 and fix it if it is affected.

What it is: CVE-2020-27846 is a critical authentication bypass vulnerability in Fedoraproject Fedora, published on 21 Dec 2020. 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-2020-27846 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/crewjam/saml (Go): affected all versions; fixed in 0.4.3
- github.com/crewjam/saml (Go): affected all versions; fixed in 0.4.3
- github.com/crewjam/saml (Go): affected all versions; fixed in 0.4.3
- grafana (Bitnami): affected all versions; fixed in 6.7.5, 7.2.3, 7.3.6

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-2020-27846/ (Markdown: https://insights.sbomify.com/CVE-2020-27846/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-27846
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-27846
- OSV: https://osv.dev/vulnerability/CVE-2020-27846

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-27846/
Summaries are generated and may contain mistakes; the official description above is the record.