CVE-2026-40179

What it is

Prometheus is an open-source monitoring system and time series database. Versions 3.0 through 3.5.1 and 3.6.0 through 3.11.1 have stored cross-site scripting vulnerabilities in multiple components of the Prometheus web UI where metric names and label values are injected into innerHTML without escaping. In both the Mantine UI and old React UI, chart tooltips on the Graph page render metric names containing HTML/JavaScript without sanitization. In the old React UI, the Metric Explorer fuzzy search results use dangerouslySetInnerHTML without escaping, and heatmap cell tooltips interpolate le label values without sanitization. With Prometheus v3.x defaulting to UTF-8 metric and label name validation, characters like <, >, and " are now valid in metric names and labels. An attacker who can inject metrics via a compromised scrape target, remote write, or OTLP receiver endpoint can execute arbitrary JavaScript in the browser of any Prometheus user who views the metric in the Graph UI, potentially enabling configuration exfiltration, data deletion, or Prometheus shutdown depending on enabled flags. This issue has been fixed in versions 3.5.2 and 3.11.2. If developers are unable to immediately update, the following workarounds are recommended: ensure that the remote write receiver (--web.enable-remote-write-receiver) and the OTLP receiver (--web.enable-otlp-receiver) are not exposed to untrusted sources; verify that all scrape targets are trusted and not under attacker control; avoid enabling admin or mutating API endpoints (e.g., --web.enable-admin-api or --web.enable-lifecycle) in environments where untrusted data may be ingested; and refrain from clicking untrusted links, particularly those containing functions such as label_replace, as they may generate poisoned label names and values.

At a glance

Exploitability

Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-04-15 23:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 10:44 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.3% in the next 30 days (EPSS).
• Severity: 5.3 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-04-15 23:16 UTC

Last modified

2026-06-17 10:44 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-79 · Cross-site scripting

Record status

Analyzed

Affected

• Prometheus < 3.5.2
• Prometheus < 3.11.2

Attack profile CVSS 4.0 · 5.3

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

Passive

Confidentiality

None

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-40179.md and follow it. Check whether this project is affected by CVE-2026-40179. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

Copy as ticket · More options · Status badge