What is CVE-2026-44903?

CVE-2026-44903 is a medium-severity vulnerability in Prometheus, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-05-26.

How severe is CVE-2026-44903?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Prometheus

CVE-2026-44903

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 ch…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.001 (16.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Prometheus — versions >= 2.49.0, < 3.5.3, >= 3.6.0-rc.0, < 3.11.3

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

security-advisories@github.com (x_refsource_CONFIRM, Patch, Mitigation, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)

Frequently asked questions

What is CVE-2026-44903?: CVE-2026-44903 is a medium-severity vulnerability in Prometheus, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-05-26.
How severe is CVE-2026-44903?: Medium severity. CVSS v3 base score is 6.1 out of 10.