How severe is CVE-2026-42052?

No CVSS score has been assigned to CVE-2026-42052 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-42052?

CVE-2026-42052 affects the following packages: beets (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-42052?

Update beets to 2.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42052 is resolved across your whole dependency graph.

How do I detect CVE-2026-42052 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for beets, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-42052 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2026-42052 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-42052 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-42052?

CVE-2026-42052 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 23th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-42052?

CVE-2026-42052 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-42052 published, and has it been updated?

CVE-2026-42052 was published on May 4, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

CVE-2026-42052 — beets

CVE-2026-42052 is a Cross-site Scripting (XSS) vulnerability in beets. A fix is available for beets — see the affected versions and patch details below.

beets is Vulnerable to XSS

Also known asGHSA-3gxm-wfjx-m847PYSEC-2026-2397

Published

May 4, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-42052.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs23th percentile — riskier than 23% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐍beets

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

During code logic analyis, an area that may lead to unintended behavior under specific conditions was discovered.

Overview

Verified Version: 80cd21554124da07d17a4f962c7d770a4f70d0f2
Vulnerability Type: Stored XSS
Affected Location: beetsplug/web/templates/index.html:42
Trigger Scenario: Metadata fields such as title, lyrics, or comments are rendered with raw template interpolation and inserted into DOM via .html(...).

Root Cause

The bundled web UI uses Underscore template interpolation mode <%= ... %> for untrusted metadata fields. In this runtime, <%= ... %> is raw insertion and HTML escaping is only performed by <%- ... %>. Rendered output is then inserted with .html(...), allowing attacker-controlled markup to become active DOM.

Source-to-Sink Chain

Source (attacker-controlled input)

Item metadata values (for example title, lyrics, comments) can contain attacker HTML payload.

Data flow

Templates in beetsplug/web/templates/index.html:42-46,87-91 render metadata with <%= ... %>.
Underscore runtime defines <%= ... %> as raw interpolation (beetsplug/web/static/underscore.js:890-907).

Sink (security-sensitive action)

Frontend inserts rendered template output into DOM via $(this.el).html(this.template(this.model.toJSON())); in beetsplug/web/static/beets.js:182,208,220.

Exploitation Preconditions

Victim opens the web UI page that renders attacker-controlled metadata.
Metadata includes executable HTML/JS payload.

Risk

Stored payload executes in the web UI context and can perform actions available to that origin.

Impact

Attacker can run arbitrary JavaScript in the victim browser, exfiltrate viewable data, and perform UI-driven actions as the victim session.

Remediation

Replace raw interpolation <%= ... %> with escaped output <%- ... %> for untrusted fields.
Avoid .html(...) for untrusted template output; use text-safe rendering.
Sanitize metadata values on ingest and before rendering, including attribute contexts.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`beets`	all versions	2.10.0`pip install --upgrade 'beets==2.10.0'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for beets, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update beets to 2.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42052 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

During code logic analyis, an area that may lead to unintended behavior under specific conditions was discovered. ## Overview - Verified Version: `80cd21554124da07d17a4f962c7d770a4f70d0f2` - Vulnerability Type: Stored XSS - Affected Location: `beetsplug/web/templates/index.html:42` - Trigger Scenario: Metadata fields such as `title`, `lyrics`, or `comments` are rendered with raw template interpolation and inserted into DOM via `.html(...)`. ## Root Cause The bundled web UI uses Underscore template interpolation mode `<%= ... %>` for untrusted metadata fields. In this runtime, `<%= ... %>` i

O3 Security · Impact-Aware SCA

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