How should we interpret CVSS severity scores?

CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

Q: What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

Q: What's the difference between a vulnerability, an exploit, and a zero-day?

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

Q: Why do vulnerabilities keep reappearing in our environment?

Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

Q: How can SynScan help reduce vulnerability risk over time?

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.

346,508

Total vulnerabilities in the database

Prometheus vulnerable to stored XSS via crafted histogram bucket label values in the old web UI heatmap display — github.com/prometheus/prometheus

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Impact

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 (e.g. via a compromised scrape target, remote write, or OTLP receiver endpoint) can execute JavaScript in the browser of any Prometheus user who views the metric in the heatmap chart UI. From the XSS context, an attacker could for example:

Read /api/v1/status/config to extract sensitive configuration (although credentials / secrets are redacted by the server)
Call /-/quit to shut down Prometheus (only if --web.enable-lifecycle is set)
Call /api/v1/admin/tsdb/delete_series to delete data (only if --web.enable-admin-api is set)
Exfiltrate metric data to an external server

Note that this only affects users who have explicitly enabled the legacy Prometheus web UI using the --enable-feature=old-ui command-line flag.

Patches

A patch is available at https://github.com/prometheus/prometheus/releases/tag/v0.311.3.

Workarounds

If at all possible, disable the legacy web UI by removing the --enable-feature=old-ui command-line flag).

If this is not an option, take the following precautions:

If using the remote write receiver (--web.enable-remote-write-receiver), ensure it is not exposed to untrusted sources.
If using the OTLP receiver (--web.enable-otlp-receiver), ensure it is not exposed to untrusted sources.
Ensure scrape targets are trusted and not under attacker control.
Do not enable admin / mutating API endpoints (e.g. --web.enable-admin-api or web.enable-lifecycle) in cases where you cannot prevent untrusted data from being ingested.
Users should avoid clicking untrusted links, especially those containing functions such as label_replace, as they may generate poisoned label names and values.

Resources

CVE-2019-10215 — prior stored DOM XSS vulnerability in Prometheus query history, fixed in v2.7.2
CVE-2026-40179 — prior stored DOM XSS vulnerability in Prometheus web UI (hover tooltips and metrics explorer), fixed in v3.11.2

Published: May 5, 2026
Updated: May 6, 2026
GHSA: GHSA-fw8g-cg8f-9j28
Severity: Medium
Exploit:

No technical information available.

CWEs:

CWE-79

OWASP TOP 10:

A7 - Cross-Site Scripting (XSS)

Affected Software
References

Software	From	Fixed in
github.com/prometheus/prometheus	-	0.311.3

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.