How severe is CVE-2026-44903?

CVE-2026-44903 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-44903 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-44903?

CVE-2026-44903 affects Prometheus. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-44903?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-44903 have an EU (EUVD) identifier?

Yes. CVE-2026-44903 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32008.

When was CVE-2026-44903 published?

CVE-2026-44903 was published on 2026-05-26 and last updated on 2026-06-17.

CVE-2026-44903

CVE-2026-44903 is a medium-severity vulnerability in Prometheus with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v4: 5.1
EPSS exploit prediction: 0% (8th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-32008
Weakness: CWE-79
Affected product: Prometheus
Published: 2026-05-26
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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 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.
How severe is CVE-2026-44903?: CVE-2026-44903 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-44903 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-44903?: CVE-2026-44903 affects Prometheus. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-44903?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-44903 have an EU (EUVD) identifier?: Yes. CVE-2026-44903 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32008.
When was CVE-2026-44903 published?: CVE-2026-44903 was published on 2026-05-26 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:prometheus:prometheus:*:*:*:*:*:*:*:*

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