How severe is GHSA-g9r4-xpmj-mj65?

No CVSS score has been assigned to GHSA-g9r4-xpmj-mj65 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-g9r4-xpmj-mj65?

GHSA-g9r4-xpmj-mj65 affects the following packages: handlebars (npm), handlebars (npm). Ecosystems affected: npm.

How do I fix GHSA-g9r4-xpmj-mj65?

Update handlebars to 3.0.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g9r4-xpmj-mj65 is resolved across your whole dependency graph.

How do I detect GHSA-g9r4-xpmj-mj65 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for handlebars. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-g9r4-xpmj-mj65 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-g9r4-xpmj-mj65?

O3 pinpoints whether GHSA-g9r4-xpmj-mj65 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-g9r4-xpmj-mj65 actively exploited in the wild?

No public exploit code has been indexed for GHSA-g9r4-xpmj-mj65 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.

When was GHSA-g9r4-xpmj-mj65 published, and has it been updated?

GHSA-g9r4-xpmj-mj65 was published on September 4, 2020 and was last updated on February 4, 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

GHSA-g9r4-xpmj-mj65

GHSA-g9r4-xpmj-mj65 is a remote code execution vulnerability in handlebars. O3 Security confirms whether GHSA-g9r4-xpmj-mj65 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Prototype Pollution in handlebars

Published

Sep 4, 2020

Updated

Feb 4, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Feb 4, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

2 pkgs 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.

17Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

handlebarsnpm

42.9Mdownloads / week

Description

Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to prototype pollution. It is possible to add or modify properties to the Object prototype through a malicious template. This may allow attackers to crash the application or execute Arbitrary Code in specific conditions.

Recommendation

Upgrade to version 3.0.8, 4.5.3 or later.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`handlebars`	all versions	3.0.8
📦npm	`handlebars`	≥ 4.0.0&&< 4.5.3	4.5.3

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for handlebars. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update handlebars to 3.0.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g9r4-xpmj-mj65 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-g9r4-xpmj-mj65 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-g9r4-xpmj-mj65. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Versions of `handlebars` prior to 3.0.8 or 4.5.3 are vulnerable to prototype pollution. It is possible to add or modify properties to the Object prototype through a malicious template. This may allow attackers to crash the application or execute Arbitrary Code in specific conditions. ## Recommendation Upgrade to version 3.0.8, 4.5.3 or later.

O3 Security · Impact-Aware SCA

Is GHSA-g9r4-xpmj-mj65 in your dependencies?

O3 detects GHSA-g9r4-xpmj-mj65 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works