CVE-2026-44903: Prometheus is an open-source monitoring system and time series database

Routine

MEDIUM 6.1UPGRADE

CVE-2026-44903 is a medium-severity flaw (CVSS 6.1) affecting prometheus. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 use

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.2% (top 90%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-05-26
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: prometheus

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-26 22:16 UTCPublished CVE record published
2026-07-24 12:10 UTCUpdated Record last modified

prometheus prometheus UPGRADE

Affected: >= 2.49.0 and < 3.5.3 · >= 3.6.0 and < 3.11.3

Fixed in: 3.5.3, 3.11.3

Safe to downgrade to: a release before 2.49.0

1. Check installed version

apt-cache policy prometheus || rpm -q prometheus || prometheus --version

2. UPGRADE to 3.5.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade prometheus

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade prometheus

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.49.0 (Debian / Ubuntu)

apt-cache madison prometheus sudo apt install prometheus=<VERSION_BEFORE_2.49.0> sudo apt-mark hold prometheus

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list prometheus sudo dnf downgrade prometheus-<VERSION_BEFORE_2.49.0> sudo dnf versionlock add prometheus

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-44903?

prometheus: upgrade to 3.5.3, 3.11.3. Exact commands for each OS are on this page.

Is CVE-2026-44903 being exploited?

CVE-2026-44903 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-44903 affect?

CVE-2026-44903 affects prometheus. Severity is medium (CVSS 6.1). 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 cha

How urgent is CVE-2026-44903?

Priority 24/100. No elevated risk signals yet.

Software pages

Prometheus vulnerabilities

Related CVEs

CVE-2026-42154 HIGH 7.5 UPGRADE Prometheus is an open-source monitoring system and time series database
CVE-2026-42151 HIGH 7.5 UPGRADE Prometheus is an open-source monitoring system and time series database
CVE-2026-40179 MEDIUM 6.1 UPGRADE Prometheus is an open-source monitoring system and time series database

References

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