Cross-site scripting in prometheus - CVE-2026-44903
Published: April 28, 2026
Vulnerability identifier: #VU128366
CSH Severity: Low
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N]
CVE-ID: CVE-2026-44903
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary JavaScript in the browser of a Prometheus user.
The vulnerability exists due to cross-site scripting in the histogram heatmap chart view of the legacy Prometheus web UI when rendering crafted histogram bucket label values in axis tick mark labels. A remote attacker can inject crafted metrics to execute arbitrary JavaScript in the browser of a Prometheus user.
Only instances with the legacy web UI enabled via the --enable-feature=old-ui flag are vulnerable.
Affected software
prometheus
How to mitigate CVE-2026-44903
Install security update from vendor's website.
prometheus - addressed in versions 3.5.3, 3.11.3