How severe is CVE-2026-48591?

No CVSS score has been assigned to CVE-2026-48591 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-48591?

CVE-2026-48591 affects the following packages: earmark (Hex). Ecosystems affected: Hex.

How do I fix CVE-2026-48591?

No patched version of earmark has shipped for CVE-2026-48591 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect CVE-2026-48591 in my Hex dependencies?

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

How do I mitigate CVE-2026-48591 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-2026-48591 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-48591 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-2026-48591?

CVE-2026-48591 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 8th 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-2026-48591?

CVE-2026-48591 is classified as CWE-83 (CWE-83). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-48591 published, and has it been updated?

CVE-2026-48591 was published on June 17, 2026 and was last updated on September 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💧 Hex

Not in CISA KEV

CVE-2026-48591 — earmark

CVE-2026-48591 is a CWE-83 vulnerability in earmark. No vendor fix is recorded yet; mitigation options are listed below.

Stored XSS via unescaped HTML attribute values in earmark

Also known asGHSA-52mm-h59v-f3c7

Published

Jun 17, 2026

Updated

Sep 8, 2026

Affected

1 pkg

Patched

See advisory

Exploits

None indexed

Exploitation data as of Oct 22, 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-2026-48591.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs8th percentile — riskier than 8% of all scored CVEsHighest risk

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

Real-World Exposure

1 pkg affected

💧earmark

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

Description

Summary

Improper Neutralization of Script in Attributes in a Web Page vulnerability in pragdave earmark allows stored cross-site scripting via unescaped HTML attribute values.

'Elixir.Earmark.Transform':_make_att1/2 in lib/earmark/transform.ex splices attribute values verbatim between two literal " bytes: [" ", name, "=\"", value, "\""]. Text nodes are routed through the existing escape function which encodes " as ", but attribute values never visit that path. A markdown link whose URL or title contains a bare " closes the attribute early and lets the trailing bytes be parsed by the browser as fresh HTML attributes. For example, [click](http://example.com/?a=x" onerror="alert(1)) renders as <a href="http://example.com/?a=x" onerror="alert(1)">click</a>, executing arbitrary JavaScript in the victim's browser.

The earmark library is no longer maintained and has been retired on Hex. No patched version will be released. All releases from 1.4.1 onward are affected, and users should migrate to a maintained Markdown library such as MDEx.

This issue affects earmark from 1.4.1 onward.

Workarounds

Migrate to a maintained Markdown library such as MDEx (https://hex.pm/packages/mdex). The earmark package has been retired on Hex and no patched release will be made.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
💧Hex	`earmark`	≥ 1.4.1	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for earmark, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of earmark has shipped for CVE-2026-48591 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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

## Summary Improper Neutralization of Script in Attributes in a Web Page vulnerability in pragdave earmark allows stored cross-site scripting via unescaped HTML attribute values. 'Elixir.Earmark.Transform':\_make\_att1/2 in lib/earmark/transform.ex splices attribute values verbatim between two literal " bytes: \[" ", name, "=\\"", value, "\\""\]. Text nodes are routed through the existing escape function which encodes " as ", but attribute values never visit that path. A markdown link whose URL or title contains a bare " closes the attribute early and lets the trailing bytes be parsed b

O3 Security · Impact-Aware SCA

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