CVE-2026-33937

CRITICALPre-NVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-03-27. A secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this weekElevated

Also known asEUVD-2026-16848 (ENISA EUVD) · GHSA-2w6w-674q-4c4q (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Public exploit or proof-of-concept code is available
CISA-KEV: Not listedEPSS PROB: 1.9%CVSS: 9.8Exploit: Public PoCExposed services: Not assessed

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, Handlebars.compile() accepts a pre-parsed AST object in addition to a template string. The value field of a NumberLiteral AST node is emitted directly into the generated JavaScript without quoting or sanitization. An attacker who can supply a crafted AST to compile() can therefore inject and execute arbitrary JavaScript, leading to Remote Code Execution on the server. Version 4.7.9 fixes the issue. Some workarounds are available. Validate input type before calling Handlebars.compile(); ensure the argument is always a string, never a plain object or JSON-deserialized value. Use the Handlebars runtime-only build (handlebars/runtime) on the server if templates are pre-compiled at build time; compile() will be unavailable.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
75
EG Risk 75/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
1.9%
EPSS %ILE
79th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
1.9% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

March 27, 2026

Last Modified

October 26, 2026

Advisory Details (8)

Auto-updated Oct 26, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github, redhat.
Red HatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 10",

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33937.json
Red HatMentions a patch (unverified)

2452523 – (CVE-2026-33937) CVE-2026-33937 handlebars.js: Handlebars: Remote Code Execution via crafted Abstract Syntax Tree object in compile()

https://bugzilla.redhat.com/show_bug.cgi?id=2452523
Red HatMentions a patch (unverified)

CVE-2026-33937 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2026-33937
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:34342
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:10175
GitHub advisoryMentions a patch (unverified)🟡 PoC Available

JavaScript Injection via AST Type Confusion in compile · Advisory · handlebars-lang/handlebars.js · GitHub

https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2w6w-674q-4c4q
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

Patch Availability(3)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatcluster-observability-operator/troubleshooting-panel-console-plugin-pf6-rhel9:17828399962026-07-01redhat
redhatdevspaces/code-rhel9:17767441102026-04-23redhat
npmhandlebars @ 4.7.9 (fixes >= 4.0.0, <= 4.7.8)—ghsa

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

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
node-handlebars3:4.7.6+~4.1.0-2 ... 3:4.7.9-5 (8 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
node-handlebars3:4.7.7+~4.1.0-1 ... 3:4.7.9-6 (7 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
node-handlebars3:4.7.7+~4.1.0-1 ... 3:4.7.9-6 (7 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
node-handlebars3:4.7.7+~4.1.0-1
  • every version up to 3:4.7.9-1: fixed in 3:4.7.9-1
—
npm(1)
PackageVulnerable rangeFix by version rangeDependents
handlebars—
  • 4.0.0 up to 4.7.9: fixed in 4.7.9
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 24× in last 7d / 77× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 99 of 228 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 129 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 20:24 UTCEG score recompute
  2. 2026-11-01 20:24 UTCVendor advisory
  3. 2026-11-01 20:24 UTCGHSA enrichmentGHSA-2w6w-674q-4c4q · GitHub severity CRITICAL · GitHub CVSS 9.8
  4. 2026-11-01 07:53 UTCGHSA enrichmentGHSA-2w6w-674q-4c4q · GitHub severity CRITICAL · GitHub CVSS 9.8
  5. 2026-11-01 07:53 UTCEG score recompute
  6. 2026-10-31 20:46 UTCEG score recompute
  7. 2026-10-31 20:46 UTCVendor advisory
  8. 2026-10-31 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  9. 2026-10-30 21:07 UTCEG score recompute
  10. 2026-10-30 21:07 UTCVendor advisory
  11. 2026-10-30 16:34 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  12. 2026-10-29 21:28 UTCEG score recompute
  13. 2026-10-29 21:28 UTCVendor advisory
  14. 2026-10-29 16:33 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  15. 2026-10-28 21:48 UTCEG score recompute
  16. 2026-10-28 21:48 UTCVendor advisory
  17. 2026-10-28 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  18. 2026-10-27 22:10 UTCEG score recompute
  19. 2026-10-27 22:10 UTCVendor advisory
  20. 2026-10-27 16:31 UTCEPSS rescoreEPSS 1.9% · 79th percentile
  21. 2026-10-26 22:26 UTCEG score recompute
  22. 2026-10-26 22:26 UTCVendor advisory
  23. 2026-10-26 15:42 UTCEG score recompute
  24. 2026-10-26 15:42 UTCVendor advisory
  25. 2026-10-25 16:32 UTCEPSS rescoreEPSS 1.9% · 79th percentile
Show 74 more
  1. 2026-10-25 16:04 UTCVendor advisory
  2. 2026-10-25 14:34 UTCEG score recompute
  3. 2026-10-24 16:32 UTCEPSS rescoreEPSS 1.8% · 78th percentile
  4. 2026-10-24 16:23 UTCVendor advisory
  5. 2026-10-23 16:44 UTCEG score recompute
  6. 2026-10-23 16:44 UTCVendor advisory
  7. 2026-10-23 16:31 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  8. 2026-10-22 17:05 UTCEG score recompute
  9. 2026-10-22 17:05 UTCVendor advisory
  10. 2026-10-22 16:34 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  11. 2026-10-21 17:24 UTCEG score recompute
  12. 2026-10-21 17:24 UTCVendor advisory
  13. 2026-10-21 16:32 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  14. 2026-10-20 17:27 UTCEG score recompute
  15. 2026-10-20 17:27 UTCVendor advisory
  16. 2026-10-20 16:33 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  17. 2026-10-19 17:46 UTCEG score recompute
  18. 2026-10-19 17:46 UTCVendor advisory
  19. 2026-10-19 16:31 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  20. 2026-10-18 18:04 UTCEG score recompute
  21. 2026-10-18 18:04 UTCVendor advisory
  22. 2026-10-18 16:31 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  23. 2026-10-18 03:46 UTCEG score recompute
  24. 2026-10-17 18:24 UTCEG score recompute
  25. 2026-10-17 18:24 UTCVendor advisory
  26. 2026-10-17 16:34 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  27. 2026-10-16 18:45 UTCEG score recompute
  28. 2026-10-16 18:45 UTCVendor advisory
  29. 2026-10-16 16:41 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  30. 2026-10-15 16:32 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  31. 2026-10-15 15:45 UTCEG score recompute
  32. 2026-10-15 15:45 UTCVendor advisory
  33. 2026-10-14 16:32 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  34. 2026-10-14 09:59 UTCEG score recompute
  35. 2026-10-14 09:59 UTCVendor advisory
  36. 2026-10-13 16:34 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  37. 2026-10-13 08:03 UTCEG score recompute
  38. 2026-10-13 08:03 UTCVendor advisory
  39. 2026-10-12 16:34 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  40. 2026-10-12 16:13 UTCEG score recompute
  41. 2026-10-12 08:24 UTCVendor advisory
  42. 2026-10-11 19:55 UTCEG score recompute
  43. 2026-10-11 17:08 UTCEG score recompute
  44. 2026-10-11 14:35 UTCEG score recompute
  45. 2026-10-11 13:48 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  46. 2026-10-10 20:00 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  47. 2026-10-09 20:07 UTCEPSS rescoreEPSS 1.7% · 77th percentile
  48. 2026-10-08 17:12 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  49. 2026-10-07 23:47 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  50. 2026-10-06 15:17 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  51. 2026-10-05 17:42 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  52. 2026-10-03 14:25 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  53. 2026-10-01 19:49 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  54. 2026-09-30 15:03 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  55. 2026-09-28 13:51 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  56. 2026-09-27 13:48 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  57. 2026-09-26 15:58 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  58. 2026-09-26 00:26 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  59. 2026-09-23 19:04 UTCOSV refresh
  60. 2026-09-18 19:28 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  61. 2026-09-17 19:30 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  62. 2026-09-16 14:08 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  63. 2026-09-16 05:15 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  64. 2026-09-15 03:11 UTCEPSS rescoreEPSS 1.7% · 75th percentile
  65. 2026-09-13 16:47 UTCEPSS rescoreEPSS 1.7% · 75th percentile
  66. 2026-09-12 15:01 UTCEPSS rescoreEPSS 1.7% · 75th percentile
  67. 2026-09-11 14:53 UTCEPSS rescoreEPSS 1.7% · 75th percentile
  68. 2026-09-11 09:37 UTCEPSS rescoreEPSS 1.7% · 75th percentile
  69. 2026-09-10 09:34 UTCEPSS rescoreEPSS 1.7% · 75th percentile
  70. 2026-09-08 22:00 UTCEPSS rescoreEPSS 1.7% · 75th percentile
  71. 2026-09-07 16:01 UTCEPSS rescoreEPSS 1.7% · 75th percentile
  72. 2026-09-06 13:47 UTCEPSS rescoreEPSS 1.7% · 75th percentile
  73. 2026-09-04 13:30 UTCEG score recompute
  74. 2026-09-04 13:30 UTCVendor advisory

Publicly available exploits

(1 reference)

Public exploit code is referenced for this CVE (1 GitHub PoC). Defenders should treat patch urgency accordingly.

  • GitHub PoCEQSTLab/CVE-2026-33937
    Published Apr 22, 2026

    Handlebars.js AST Injection Remote Code Execution Vulnerability

    Open source ↗

Frequently asked(5)

What is CVE-2026-33937?
CVE-2026-33937 is a critical-severity vulnerability; its CVE record was 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, Handlebars.compile() accepts a pre-parsed AST object in addition to a template string. The value field of a NumberLiteral AST node is emitted directly into the generated JavaScript…
When was the CVE record for CVE-2026-33937 published?
The CVE record for CVE-2026-33937 was published on March 27, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-33937 actively exploited?
CVE-2026-33937 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.9% probability of exploitation in the next 30 days (79th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-33937?
CVE-2026-33937 has a CVSS base score of 9.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-33937?
A fix for CVE-2026-33937 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-33937 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-33937

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