Description
Prometheus is an open-source monitoring system and time series database. From 2.49.0 to before 3.5.3 and 3.11.3, in the Prometheus server's legacy web UI (enabled via the command-line flag --enable-feature=old-ui), the histogram heatmap chart view does not escape le label values when inserting them into the HTML for use as axis tick mark labels. An attacker who can inject crafted metrics can execute JavaScript in the browser of any Prometheus user who views the metric in the heatmap chart UI. This vulnerability is fixed in 3.5.3 and 3.11.3.
Published: 2026-05-26
Score: 5.1 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-fw8g-cg8f-9j28 Prometheus vulnerable to stored XSS via crafted histogram bucket label values in the old web UI heatmap display
History

Tue, 26 May 2026 21:45:00 +0000

Type Values Removed Values Added
Description Prometheus is an open-source monitoring system and time series database. From 2.49.0 to before 3.5.3 and 3.11.3, in the Prometheus server's legacy web UI (enabled via the command-line flag --enable-feature=old-ui), the histogram heatmap chart view does not escape le label values when inserting them into the HTML for use as axis tick mark labels. An attacker who can inject crafted metrics can execute JavaScript in the browser of any Prometheus user who views the metric in the heatmap chart UI. This vulnerability is fixed in 3.5.3 and 3.11.3.
Title Prometheus: Stored XSS via crafted histogram bucket label values in the heatmap display of the old Prometheus web UI
Weaknesses CWE-79
References
Metrics cvssV4_0

{'score': 5.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N'}


Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-26T21:27:18.597Z

Reserved: 2026-05-07T21:50:33.547Z

Link: CVE-2026-44903

cve-icon Vulnrichment

No data.

cve-icon NVD

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cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses