Disclosure summary
### 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 scrape target or remote write. With Prometheus v3.x defaulting to UTF-8 metric and label name validation, characters like ``, and `"` are now valid in metric names and lab
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
GitHub Reviewed Security Advisories · GHSA-vffh-x6r8-xx99
Open original source · Updated Oct 06, 2026
Prometheus has Stored XSS via metric names and label values in Prometheus web UI tooltips and metrics explorer
Source severity: MEDIUM / 5.3
| Ecosystem | Package | Affected range | First patched |
|---|---|---|---|
| go | github.com/prometheus/prometheus | >= 3.0.0, | 3.5.2 |
| go | github.com/prometheus/prometheus | >= 3.6.0, | 3.11.2 |
| go | github.com/prometheus/prometheus | < 0.311.2-0.20260410083055-07c6232d159b | 0.311.2-0.20260410083055-07c6232d159b |
Microsoft Security Updates (CVRF) · 2026-Apr
Open original source · Updated Sep 24, 2026
Prometheus: Stored XSS via metric names and label values in web UI tooltips and metrics explorer
Maximum of vendor-reported product scores; products and fixed builds are associations, not a universal affected-version statement.
| Vendor | Product / association | Version / bounds |
|---|---|---|
| Microsoft update guide | cbl2 prometheus 2.37.9-7 on CBL Mariner 2.0 | (MSRC status code 3) |
| Microsoft update guide | cbl2 prometheus 2.37.9-7 on CBL-Mariner 2.0 | (MSRC status code 3) |
Vendor remediation references
- Release Notes · product IDs 21009-21692
- Vendor guidance · product IDs 21009-21692
Original records & references
- NIST NVD record
- CVE Program record
- github.com — Reviewed advisory
PUBLISHED 2026-04-13T12:39:16-04:00
MODIFIED 2026-10-06T14:47:28-04:00
INGESTED 2026-10-08T12:05:11-04:00