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Vulnerabilities

Vulnerability · CVE-2026-44903

Prometheus is an open-source monitoring system and time series database.

Published May 26, 2026 · catalog updated Jul 24, 2026 · Prometheus is an open-source

Check if you run it

No confirmed exploitation is on record for CVE-2026-44903. EPSS is 0.24%. Act only if a listed version of Prometheus is an open-source is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Prometheus is an open-source).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.24%
Remediation
Advisory link
Affected products
cpe prometheus/prometheus

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe prometheus/prometheusversion unspecified

How to fix CVE-2026-44903

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-44903. EPSS is 0.24%. Act only if a listed version of Prometheus is an open-source is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-79: Cross-site Scripting (XSS). EPSS 0.24%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 26, 2026 · NIST NVD

    Detected

    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 execu

  2. Jul 24, 2026 · NIST NVD

    Updated

    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 execu

Sources

  • CVE.orgVulnerability recordCVE-2026-44903

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-44903

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-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 chart view does not escape le label values

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.