# CVE-2022-23635: Unauthenticated control plane denial of service attack in Istio

> Unauthenticated attackers can crash the Istio control plane by sending specially crafted messages to an exposed TLS port, causing denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 22 Feb 2022
- **Updated:** 23 Apr 2025
- **Also known as:** GHSA-856q-xv3c-7f2f, MINI-5mw8-jwcq-jjmj, MINI-9gfr-m7j2-fqqf

## What is CVE-2022-23635?

CVE-2022-23635 is a high-severity denial of service vulnerability in istio, published on 22 Feb 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Istio is an open platform to connect, manage, and secure microservices. In affected versions the Istio control plane, `istiod`, is vulnerable to a request processing error, allowing a malicious attacker that sends a specially crafted message which results in the control plane crashing. This endpoint is served over TLS port 15012, but does not require any authentication from the attacker. For simple installations, Istiod is typically only reachable from within the cluster, limiting the blast radius. However, for some deployments, especially [multicluster](https://istio.io/latest/docs/setup/install/multicluster/primary-remote/) topologies, this port is exposed over the public internet. There are no effective workarounds, beyond upgrading. Limiting network access to Istiod to the minimal set of clients can help lessen the scope of the vulnerability to some extent.

Weakness: CWE-1284 (Improper Validation of Specified Quantity in Input), CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2022-23635?

6 open source packages ship an affected version, including istio.io/istio. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `istio.io/istio` | Go | All versions | 1.11.7 |
| `istio.io/istio` | Go | All versions | 1.11.7 |
| `istio.io/istio` | Go | From 1.12.0 | 1.12.4 |
| `istio.io/istio` | Go | From 1.12.0 | 1.12.4 |
| `istio.io/istio` | Go | From 1.13.0 | 1.13.1 |
| `istio.io/istio` | Go | From 1.13.0 | 1.13.1 |

Products: Istio Istio.

## How do I fix CVE-2022-23635?

Upgrade istio.io/istio to a fixed version for your release line: 1.11.7, 1.12.4 or 1.13.1.

## Is CVE-2022-23635 being exploited?

There is no known exploitation of CVE-2022-23635 in the wild and no public exploit code.

## Other vulnerabilities in istio

- [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-2022-23635 and fix it if it is affected.

What it is: CVE-2022-23635 is a high-severity denial of service vulnerability in istio, published on 22 Feb 2022. 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-2022-23635 in the wild and no public exploit code.

Affected packages and fixed versions:
- istio.io/istio (Go): affected all versions; fixed in 1.11.7
- istio.io/istio (Go): affected all versions; fixed in 1.11.7
- istio.io/istio (Go): affected from 1.12.0; fixed in 1.12.4
- istio.io/istio (Go): affected from 1.12.0; fixed in 1.12.4
- istio.io/istio (Go): affected from 1.13.0; fixed in 1.13.1
- istio.io/istio (Go): affected from 1.13.0; fixed in 1.13.1

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-2022-23635/ (Markdown: https://insights.sbomify.com/CVE-2022-23635/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-23635
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-23635
- OSV: https://osv.dev/vulnerability/CVE-2022-23635

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-23635/
Summaries are generated and may contain mistakes; the official description above is the record.