CVE-2026-44903

Name	CVE-2026-44903
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1138261

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
prometheus (PTS)	bullseye	2.24.1+ds-1	fixed
	bookworm	2.42.0+ds-5	fixed
	trixie	2.53.3+ds1-2	vulnerable
	forky, sid	2.53.5+ds1-5	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Debian Bugs
prometheus	source	bullseye	(not affected)
prometheus	source	bookworm	(not affected)
prometheus	source	(unstable)	(unfixed)	1138261

Notes

[bookworm] - prometheus <not-affected> (Vulnerable code introduced later)
[bullseye] - prometheus <not-affected> (Vulnerable code introduced later)
https://github.com/prometheus/prometheus/security/advisories/GHSA-fw8g-cg8f-9j28
Fixed by: https://github.com/prometheus/prometheus/commit/38f23b9075ced1de2b82d2dad8b2bebb1ecd5b7d
Introduced by: https://github.com/prometheus/prometheus/commit/2e205ee95c121d8d6da0d8984f0b3bc599acaa2a (v2.49.0-rc.0)