What is CVE-2026-84370?

CVE-2026-84370 is a high-severity cross-site scripting (XSS) vulnerability in svgo (npm), affecting versions >= 1.0.0, < 2.8.4. It is fixed in 2.8.4, 3.3.5, 4.1.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.

How severe is CVE-2026-84370?

CVE-2026-84370 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of svgo are affected by CVE-2026-84370?

svgo (npm) versions >= 1.0.0, < 2.8.4 is affected.

Is there a fix for CVE-2026-84370?

Yes. CVE-2026-84370 is fixed in 2.8.4, 3.3.5, 4.1.0. Upgrade to this version or later.

Is CVE-2026-84370 exploitable, and should I be worried?

Whether CVE-2026-84370 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2026-84370 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

How do I fix CVE-2026-84370?

Upgrade: svgo to 2.8.4 or later, svgo to 3.3.5 or later, svgo to 4.1.0 or later.

CVE-2026-84370 in svgo

Q: How severe is CVE-2026-84370?

CVE-2026-84370 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Q: Which versions of svgo are affected by CVE-2026-84370?

svgo (npm) versions >= 1.0.0, < 2.8.4 is affected.

Q: Is there a fix for CVE-2026-84370?

Yes. CVE-2026-84370 is fixed in 2.8.4, 3.3.5, 4.1.0. Upgrade to this version or later.

Q: Is CVE-2026-84370 exploitable, and should I be worried?

Whether CVE-2026-84370 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2026-84370 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2026-84370?

Upgrade: svgo to 2.8.4 or later, svgo to 3.3.5 or later, svgo to 4.1.0 or later.

Summary

SVGO: removeScripts allows executable links through namespace and control-character bypasses

SVGO's opt-in removeScripts plugin failed to remove some executable links. Namespace-prefixed SVG anchors and URL schemes containing ASCII tabs or newlines could bypass its checks. Applications that used this plugin as their only protection for untrusted SVG input could expose users to cross-site scripting (XSS).

SVGO is an optimizer rather than a comprehensive sanitization library, but removeScripts is maintained for consumers that already rely on it to remove common script execution paths.

Details

Two related bypasses were present:

The plugin inspected unprefixed SVG <a> elements but did not recognize namespace-prefixed SVG anchors such as <svg:a> when the prefix was bound to the SVG namespace. Their executable href or namespaced *:href values remained intact.
The URL check did not account for ASCII tab, line-feed, or carriage-return characters embedded in a scheme. Browsers remove these characters before parsing the scheme, so values such as java	script: could remain executable after bypassing the plugin's javascript: check.

Anchors in unrelated custom namespaces are not executable SVG anchors and remain untouched.

Workarounds

For hostile input, use a dedicated SVG sanitization tool before passing the SVG to SVGO. Applications can also reject links from untrusted SVG input and avoid serving user-controlled SVGs in an active same-origin context.

References

v4 fix: https://github.com/svg/svgo/pull/2268
related executable URL hardening: https://github.com/svg/svgo/pull/2263
v3 backport: https://github.com/svg/svgo/pull/2269
v2 backport: https://github.com/svg/svgo/pull/2272
v4.1.0 release: https://github.com/svg/svgo/releases/tag/v4.1.0
v3.3.5 release: https://github.com/svg/svgo/releases/tag/v3.3.5
v2.8.4 release: https://github.com/svg/svgo/releases/tag/v2.8.4

Impact

If an application optimized attacker-controlled SVGs with removeScripts and then served the result in an active browser context, a victim could follow a link that executes script in the SVG's origin. Depending on the embedding and origin configuration, this could expose cookies or local storage, modify content, or perform actions as the victim.

The plugin is opt-in, so consumers that do not enable it are not relying on the affected behavior. Typical local optimization of trusted SVG files is not affected.

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2026-84370 has a CVSS score of 8.2 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.8.4, 3.3.5, 4.1.0); upgrading removes the vulnerable code path.

Affected versions

svgo (>= 1.0.0, < 2.8.4) svgo (>= 3.0.0, < 3.3.5) svgo (>= 4.0.0, < 4.1.0)

Security releases

svgo → 2.8.4 (npm) svgo → 3.3.5 (npm) svgo → 4.1.0 (npm)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade to one of the following releases for the maintained release line in use:

Release line	Patched version	Plugin
v2	2.8.4	`removeScriptElement`
v3	3.3.5	`removeScriptElement`
v4	4.1.0	`removeScripts`

The fix makes SVG anchor handling namespace-aware and strips ASCII tabs, line feeds, and carriage returns before checking executable URL schemes.

SVGO v1 is no longer maintained. Users of v1 should upgrade to a supported release line.

Frequently Asked Questions

What is CVE-2026-84370? CVE-2026-84370 is a high-severity cross-site scripting (XSS) vulnerability in svgo (npm), affecting versions >= 1.0.0, < 2.8.4. It is fixed in 2.8.4, 3.3.5, 4.1.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
How severe is CVE-2026-84370? CVE-2026-84370 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of svgo are affected by CVE-2026-84370? svgo (npm) versions >= 1.0.0, < 2.8.4 is affected.
Is there a fix for CVE-2026-84370? Yes. CVE-2026-84370 is fixed in 2.8.4, 3.3.5, 4.1.0. Upgrade to this version or later.
Is CVE-2026-84370 exploitable, and should I be worried? Whether CVE-2026-84370 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2026-84370 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2026-84370?
- Upgrade svgo to 2.8.4 or later
- Upgrade svgo to 3.3.5 or later
- Upgrade svgo to 4.1.0 or later