# CVE-2020-8843: Security feature bypass in n/a

> Attackers can bypass Mixer policies by injecting headers, requiring specific non-default configurations in Istio service mesh deployments.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/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:** 14 Feb 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-8hpm-7f4v-97xg

## What is CVE-2020-8843?

CVE-2020-8843 is a high-severity vulnerability in n/a, published on 14 Feb 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in Istio 1.3 through 1.3.6. Under certain circumstances, it is possible to bypass a specifically configured Mixer policy. Istio-proxy accepts the x-istio-attributes header at ingress that can be used to affect policy decisions when Mixer policy selectively applies to a source equal to ingress. To exploit this vulnerability, someone has to encode a source.uid in this header. This feature is disabled by default in Istio 1.3 and 1.4.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-8843?

It affects 1 product.


Products: Istio Istio.

## How do I fix CVE-2020-8843?

No fix has been published for CVE-2020-8843 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-8843 being exploited?

There is no known exploitation of CVE-2020-8843 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-31921](https://insights.sbomify.com/CVE-2021-31921/): Missing authorization in n/a (critical 9.8)
- [CVE-2021-34824](https://insights.sbomify.com/CVE-2021-34824/): Information disclosure in n/a (high 8.8)
- [CVE-2026-31837](https://insights.sbomify.com/CVE-2026-31837/): Istio JWKS resolver to prevent private key material from being exposed when JWKS fetch fails. (high 8.7)
- [CVE-2021-39155](https://insights.sbomify.com/CVE-2021-39155/): Authorization Policy Bypass Due to Case Insensitive Host Comparison (high 8.3)
- [CVE-2021-39156](https://insights.sbomify.com/CVE-2021-39156/): Fragments in Path May Lead to Authorization Policy Bypass (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-8843 and fix it if it is affected.

What it is: CVE-2020-8843 is a high-severity vulnerability in n/a, published on 14 Feb 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-2020-8843 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-2020-8843/ (Markdown: https://insights.sbomify.com/CVE-2020-8843/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8843
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8843
- OSV: https://osv.dev/vulnerability/CVE-2020-8843

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-8843/
Summaries are generated and may contain mistakes; the official description above is the record.