CVE-2026-33939

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6%, top 54% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: Elevated riskExposed: 0

A fix is available — apply it.

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. {{*n}}), the compiled template calls lookupProperty(decorators, "n"), which returns undefined. The runtime then immediately invokes the result as a function, causing an unhandled TypeError: ... is not a function that crashes the Node.js process. Any application that compiles user-supplied templates without wrapping the call in a try/catch is vulnerable to a single-request Denial of Service. Version 4.7.9 fixes the issue. Some workarounds are available. Wrap compilation and rendering in try/catch. Validate template input before passing it to compile(); reject templates containing decorator syntax ({{*...}}) if decorators are not used in your application. Use the pre-compilation workflow; compile templates at build time and serve only pre-compiled templates; do not call compile() at request time.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
46%
KEV
Not listed

Published

March 27, 2026

Last Modified

July 15, 2026

Advisory Details (8)

Auto-updated Jul 7, 2026
🔬 Proof of concept available. Patch available. Sources: github_release, github, redhat, github_commit.
redhat Patch Available

Affected: Red Hat Enterprise Linux 10",

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33939.json
github Patch Available🟡 PoC Available

Denial of Service via Malformed Decorator Syntax in Template Compilation · Advisory · handlebars-lang/handlebars.js · GitHub

https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff
redhat Patch Available

2452508 – (CVE-2026-33939) CVE-2026-33939 handlebars.js: Handlebars.js: Denial of Service via malformed decorator syntax in template compilation

https://bugzilla.redhat.com/show_bug.cgi?id=2452508
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-33939
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:34342
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:10175
github_release Patch Available

v4.7.9

Patch available: handlebars-lang/handlebars.js v4.7.9

https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9
github_commit Patch Available

commit 68d8df5a88e0 (handlebars-lang/handlebars.js)

Patch available: handlebars-lang/handlebars.js v4.7.9 (contains commit 68d8df5a88e0)

https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2

Vendor Advisories for CVE-2026-33939(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatdevspaces/code-rhel9:17767441102026-04-23redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
handlebars—4.7.9—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 39× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-26 14:54 UTCEPSS rescore
  2. 2026-07-26 14:54 UTCEPSS rescore
  3. 2026-07-25 14:18 UTCEPSS rescore
  4. 2026-07-25 14:18 UTCEPSS rescore
  5. 2026-07-24 14:17 UTCEPSS rescore
  6. 2026-07-24 14:17 UTCEPSS rescore
  7. 2026-07-23 14:18 UTCEPSS rescore
  8. 2026-07-23 14:18 UTCEPSS rescore
  9. 2026-07-23 03:09 UTCEG score recompute
  10. 2026-07-22 14:08 UTCEPSS rescore
  11. 2026-07-21 15:24 UTCEPSS rescore
  12. 2026-07-20 17:08 UTCEPSS rescore
  13. 2026-07-19 14:31 UTCEPSS rescore
  14. 2026-07-19 02:29 UTCEPSS rescore
  15. 2026-07-18 10:04 UTCEPSS rescore
  16. 2026-07-18 06:59 UTCOSV refresh
  17. 2026-07-16 17:03 UTCEPSS rescore
  18. 2026-07-15 16:57 UTCEPSS rescore
  19. 2026-07-15 16:57 UTCEPSS rescore
  20. 2026-07-15 02:00 UTCEPSS rescore
  21. 2026-07-13 22:30 UTCEPSS rescore
  22. 2026-07-13 06:13 UTCEPSS rescore
  23. 2026-07-13 06:13 UTCEPSS rescore
  24. 2026-07-12 05:46 UTCEPSS rescore
  25. 2026-07-11 08:27 UTCEPSS rescore
Show 14 more
  1. 2026-07-09 19:10 UTCEPSS rescore
  2. 2026-07-08 15:15 UTCEPSS rescore
  3. 2026-07-07 13:46 UTCEPSS rescore
  4. 2026-07-06 16:27 UTCEPSS rescore
  5. 2026-07-06 16:27 UTCEPSS rescore
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-06 02:23 UTCEPSS rescore
  8. 2026-07-05 02:30 UTCEPSS rescore
  9. 2026-07-04 06:31 UTCEPSS rescore
  10. 2026-07-01 15:06 UTCEPSS rescore
  11. 2026-06-30 23:22 UTCEPSS rescore
  12. 2026-06-30 04:36 UTCEG score recompute
  13. 2026-06-30 04:36 UTCVendor advisory
  14. 2026-06-30 04:32 UTCNVD updatefirst tracked

Frequently asked(5)

What is CVE-2026-33939?
CVE-2026-33939 is a high vulnerability published on March 27, 2026. Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. {{n}}), the compiled template calls lookupProperty(decorators, "n"), which returns…
When was CVE-2026-33939 disclosed?
CVE-2026-33939 was first published in the National Vulnerability Database on March 27, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33939 actively exploited?
CVE-2026-33939 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.1% of all scored CVEs.
What is the CVSS score of CVE-2026-33939?
CVE-2026-33939 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-33939?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33939, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-33939

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