Cross-site Scripting (XSS) Affecting mc package, versions <0.20250813.083541-r11


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.15% (5th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-MC-16718688
  • published17 May 2026
  • disclosed26 May 2026

Introduced: 17 May 2026

CVE-2026-44903  (opens in a new tab)
CWE-79  (opens in a new tab)

How to fix?

Upgrade Chainguard mc to version 0.20250813.083541-r11 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream mc package and not the mc package as distributed by Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1