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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-44903

27
FAUCET Score

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.

First published: May 26, 2026Last modified: May 26, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 2.49.0, < 3.5.3CPE matchmatch criteria
cpe:2.3:a:prometheus:prometheus:*:*:*:*:*:*:*:*
>= 3.6.0, < 3.11.3CPE matchmatch criteria
cpe:2.3:a:prometheus:prometheus:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

5.1MEDIUM

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
PASSIVE
VS Confidentiality
NONE
VS Integrity
NONE
VS Availability
NONE
SS Confidentiality
LOW
SS Integrity
LOW
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.18%
Probability of exploitation in next 30 days
EPSS Percentile
8.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0018 is in the 7th percentile among its peer group of 26,221 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
gopatch availablevia ghsa
Product: github.com/prometheus/prometheusFixed in: 0.311.3

Vendor Advisories (1)

goGHSA-fw8g-cg8f-9j28medium

Prometheus vulnerable to stored XSS via crafted histogram bucket label values in the old web UI heatmap display

May 5, 2026

References

github.com / prometheus/prometheus/commit/38f23b9075ced1de2b82d2dad8b2bebb1ecd5b7d
Patch
github.com / prometheus/prometheus/security/advisories/GHSA-fw8g-cg8f-9j28
MitigationPatchVendor Advisory