Summary
Workarounds
Users who can not upgrade can switch to Managed Identity or Workload Identity authentication for Azure AD remote write, which do not involve a client secret.
Impact
Users who use Azure AD remote write with OAuth authentication are impacted.
The client_secret field in the Azure AD remote write OAuth configuration (storage/remote/azuread) was typed as string instead of Secret. Prometheus redacts fields of type Secret when serving the configuration via the /-/config HTTP API endpoint. Because the field was a plain string, the Azure OAuth client secret was exposed in plaintext to any user or process with access to that endpoint.
CVE-2026-42151 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.311.3); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
The problem has been patched by changing ClientSecret in OAuthConfig to Secret. Users should upgrade to 3.11.3 or 3.5.3 LTS.
Frequently Asked Questions
- What is CVE-2026-42151? CVE-2026-42151 is a high-severity security vulnerability in github.com/prometheus/prometheus (go), affecting versions >= 0.45.2, < 0.311.3. It is fixed in 0.311.3.
- How severe is CVE-2026-42151? CVE-2026-42151 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/prometheus/prometheus are affected by CVE-2026-42151? github.com/prometheus/prometheus (go) versions >= 0.45.2, < 0.311.3 is affected.
- Is there a fix for CVE-2026-42151? Yes. CVE-2026-42151 is fixed in 0.311.3. Upgrade to this version or later.
- Is CVE-2026-42151 exploitable, and should I be worried? Whether CVE-2026-42151 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-42151 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-42151? Upgrade
github.com/prometheus/prometheusto 0.311.3 or later.