How severe is CVE-2026-59710?

No CVSS score has been assigned to CVE-2026-59710 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-59710?

CVE-2026-59710 affects the following packages: showdown (npm). Ecosystems affected: npm.

How do I fix CVE-2026-59710?

No patched version of showdown has shipped for CVE-2026-59710 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-2026-59710 in my npm dependencies?

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

How do I mitigate CVE-2026-59710 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-2026-59710 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-59710 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-2026-59710?

CVE-2026-59710 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 25th 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-2026-59710?

CVE-2026-59710 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-2026-59710 published, and has it been updated?

CVE-2026-59710 was published on July 6, 2026 and was last updated on August 19, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

CVE-2026-59710 — showdown

Fix: showdownjs/showdown@e5cab1e

CVE-2026-59710 is a Cross-site Scripting (XSS) vulnerability in showdown. No vendor fix is recorded yet; mitigation options are listed below.

showdown - Stored XSS via Unescaped Table Header ID Attribute Injection

Also known asGHSA-22g5-r2x5-97cx

Published

Jul 6, 2026

Updated

Aug 19, 2026

Affected

1 pkg

Patched

See advisory

Exploits

None indexed

Exploitation data as of Oct 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-59710.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs25th percentile — riskier than 25% of all scored CVEsHighest risk

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

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

1Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

showdownnpm

1.6Mdownloads / week

Description

showdown contains a stored cross-site scripting vulnerability in the parseHeaders function of src/subParsers/makehtml/tables.js that fails to properly escape table header ID attributes. Attackers can inject arbitrary HTML and script-executing SVG elements through double-quote characters in markdown table headers, achieving stored XSS when untrusted markdown is rendered with the default github flavor configuration.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
📦npm	`showdown`	all versions	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 showdown, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of showdown has shipped for CVE-2026-59710 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.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Showdown, as integrated into Red Hat products, is susceptible to a stored cross-site scripting vulnerability. This flaw allows an attacker to inject arbitrary HTML and script-executing SVG elements by exploiting unescaped table header ID attributes within markdown. When untrusted markdown is rendered using the default…

Workaround published by Red Hat

To mitigate this vulnerability, avoid rendering untrusted markdown content within applications utilizing Showdown. If processing untrusted markdown is unavoidable, ensure that all input is thoroughly sanitized before rendering to prevent the injection of malicious HTML or script-executing elements.

Source: Red Hat security advisory for CVE-2026-59710 (CC BY 4.0)

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2026-59710 in your dependencies?

Find it across npm, including transitive dependencies.

Scan my dependencies How O3 SCA works