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npm package

handlebars 1.0.9 vulnerabilities, and the version that fixes all of them

handlebars 1.0.9 has 9 known vulnerabilities (8 rated high or critical); 4.7.7 fixes all of them. 4.7.7 has 11 known vulnerabilities of its own, so upgrade to 4.7.10, which has none.

npm (opens in a new tab) describes it as “Handlebars provides the power necessary to let you build semantic templates effectively with no frustration”

Known vulnerabilities
9
8 rated high or critical
Released
Feb 16, 2013
Latest is 4.7.10
Downloads last week
329
Under 1% of handlebars downloads
Licence
MIT
OpenSSF Scorecard
5.2/10
wycats/handlebars.js (opens in a new tab)
Pulls in
3 packages
Resolved by deps.dev

What to upgrade to

4.7.10 is the closest release with no known vulnerabilities that we checked.

  • 1.3.0

    Newest 1.x release. Released Jan 2, 2014.

    9 known vulnerabilities, worst rated warning

  • 4.7.7

    Fixes all 9 known vulnerabilities. Released Feb 15, 2021.

    11 known vulnerabilities, worst rated warning

  • 4.7.10Upgrade to this

    Latest release. Released Oct 5, 2026.

    No known vulnerabilities

4.7.10 came out on Oct 5, 2026. A coding agent trained before then doesn’t know it exists, so it may suggest an older release. AI knowledge cutoff dates

Hand the fix to your coding agent

One task with the upgrade, the file to change and why. Paste it into Claude Code, Cursor or Codex.

Findings

Every advisory for handlebars 1.0.9

Known exploited first (CISA KEV), then by how likely they are to be exploited (FIRST EPSS), then by severity. Each id links to its OSV.dev record.

  1. CriticalCVE-2019-19919 on OSV.dev (opens in a new tab)GHSA-w457-6q6x-cgp9EPSS: top 6%

    Prototype Pollution in handlebars

    Fixed in 3.0.8. Published Dec 26, 2019.

  2. CriticalCVE-2021-23369 on OSV.dev (opens in a new tab)GHSA-f2jv-r9rf-7988EPSS: top 6%

    Remote code execution in handlebars when compiling templates

    Fixed in 4.7.7. Published May 6, 2021.

  3. CriticalCVE-2021-23383 on OSV.dev (opens in a new tab)GHSA-765h-qjxv-5f44EPSS: top 9%

    Prototype Pollution in handlebars

    Fixed in 4.7.7. Published Feb 10, 2022.

  4. CriticalCVE-2019-20920 on OSV.dev (opens in a new tab)GHSA-3cqr-58rm-57f8EPSS: top 13%

    Arbitrary Code Execution in Handlebars

    Fixed in 3.0.8. Published Feb 10, 2022.

  5. WarningCVE-2015-8861 on OSV.dev (opens in a new tab)GHSA-9prh-257w-9277EPSS: top 15%

    Cross-Site Scripting in handlebars

    Fixed in 4.0.0. Published Oct 23, 2018.

  6. CriticalGHSA-q2c6-c6pm-g3gh on OSV.dev (opens in a new tab)

    Arbitrary Code Execution in handlebars

    Fixed in 3.0.8. Published Sep 4, 2020.

  7. CriticalGHSA-g9r4-xpmj-mj65 on OSV.dev (opens in a new tab)

    Prototype Pollution in handlebars

    Fixed in 3.0.8. Published Sep 4, 2020.

  8. CriticalGHSA-2cf5-4w76-r9qv on OSV.dev (opens in a new tab)

    Arbitrary Code Execution in handlebars

    Fixed in 3.0.8. Published Sep 4, 2020.

  9. CriticalGHSA-q42p-pg8m-cqh6 on OSV.dev (opens in a new tab)

    Prototype Pollution in handlebars

    Fixed in 3.0.7. Published Jun 5, 2019.

Who is still on a vulnerable handlebars

83% of last week’s 43.4M handlebars downloads went to versions with known vulnerabilities.

From npm’s per-version download counts for the last 7 days, each version checked against OSV.dev. The versions checked cover over 99% of downloads.

Is handlebars the only one?

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How this page is checked

StackPrism asks OSV.dev which advisories affect exactly handlebars 1.0.9, merges duplicates filed under several ids, and ranks them with CISA’s Known Exploited Vulnerabilities list and FIRST EPSS. Release dates and deprecation come from deps.dev and npm. No AI writes this page: every sentence comes from that data, refreshed every few hours.

Last checked against npm, OSV.dev, deps.dev, CISA KEV and FIRST EPSS.