CVE-2026-44903 MEDIUM

CVE-2026-44903: Prometheus: Stored XSS via crafted histogram bucket label values in the heatmap display of the old Prometheus web UI

Vendor Prometheus
Product prometheus
Weakness CWE-79 · XSS
Published May 26, 2026
Last update May 27, 2026
View on NVD All CVEs

CVSS base score

5.1/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction —
Confidentiality —
Integrity —

CVSS 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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

May 26, 2026 CVE published
May 27, 2026 Record updated

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04Related CVE

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