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Medium, CVSS 5.3

Prometheus has Stored XSS via metric names and label values in Prometheus web UI tooltips and metrics explorer

CVE-2026-40179GHSA-vffh-x6r8-xx99

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/prometheus/prometheus 3.11.2, 3.5.2, 0.311.2-0.20260410083055-07c6232d159b), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • Go github.com/prometheus/prometheus

    Affected
    >= 3.0.0, <= 3.5.1>= 3.6.0, <= 3.11.1< 0.311.2-0.20260410083055-07c6232d159b
    Fixed in
    3.5.2, 0.311.2-0.20260410083055-07c6232d159b, 3.11.2

Sources

  • GitHub Advisory Database and maintainer security advisories on GitHub

    GitHub-reviewed advisory GHSA-vffh-x6r8-xx99 lists affected ranges: Go github.com/prometheus/prometheus >=3.0.0 =3.6.0 =0 <0.311.2-0.20260410083055-07c6232d159b

    VerifiedObserved Structured GitHub Advisory Database record (type=reviewed) from the GitHub REST API.

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N · score source
EPSS
  • CVE-2026-40179: 0.31% estimated exploitation activity in the next 30 days; percentile 23.97 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact Stored cross-site scripting (XSS) via crafted metric names in the Prometheus web UI: Old React UI + New Mantine UI: When a user hovers over a chart tooltip on the Graph page, metric names containing HTML/JavaScript are injected into innerHTML without escaping, causing arbitrary script execution in the user's browser. Old React UI only: When a user opens the Metric Explorer (globe icon next to the PromQL expression input field), and a metric name containing HTML/JavaScript is rendered in the fuzzy search results, it is injected into innerHTML without escaping, causing arbitrary script execution in the user's browser. Old React UI only: When a user views a heatmap chart and hovers over a cell, the le label values of the underlying histogram buckets are interpolated into innerHTML without escaping. While le is conventionally a numeric bucket boundary, Prometheus does not enforce this — arbitrary UTF-8 strings are accepted as label values, allowing script injection via a crafted…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-vffh-x6r8-xx99

Agent brief

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# Patch Next advisory brief: CVE-2026-40179

Advisory: Prometheus has Stored XSS via metric names and label values in Prometheus web UI tooltips and metrics explorer
IDs: CVE-2026-40179, GHSA-vffh-x6r8-xx99
Record: https://patchnext.com/advisories/cve-2026-40179 (revision 1, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/prometheus/prometheus 3.11.2, 3.5.2, 0.311.2-0.20260410083055-07c6232d159b. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/prometheus/prometheus: affected >= 3.0.0, <= 3.5.1; >= 3.6.0, <= 3.11.1; < 0.311.2-0.20260410083055-07c6232d159b; fixed in 3.5.2, 0.311.2-0.20260410083055-07c6232d159b, 3.11.2

## Suggested inspection (read-only)
- Go github.com/prometheus/prometheus: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/prometheus/prometheus.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-vffh-x6r8-xx99 (GitHub-reviewed advisory GHSA-vffh-x6r8-xx99 lists affected ranges: Go github.com/prometheus/prometheus >=3.0.0 =3.6.0 =0 <0.311.2-0.20260410083055-07c6232d159b)

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