CVE-2021-23383 | Prototype Pollution

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The package handlebars before 4.7.7 are vulnerable to Prototype Pollution when selecting certain compiling options to compile templates coming from an untrusted source.

Published: 2021-05-04 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-23383 is rated High Exploit Risk (71.5/100): CVSS Medium severity, with high exploitation likelihood (EPSS 5.67%, 90th percentile). 4 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +2.49% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-23383

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-23383

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-03 3.18% 5.67% +2.49%
2 2026-03-04 4.62% 3.18% -1.44%
3 2026-03-01 — 4.62% —

Full EPSS history (53 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-23383

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.6 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 2.2 3.4 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2021-23383

GitHub Security Advisory for CVE-2021-23383

GHSA-765h-qjxv-5f44 · Severity: critical · Ecosystem: npm — Prototype Pollution in handlebars

OS Trackers for CVE-2021-23383

vendor priority summary link
debian not yet assigned CVE-2021-23383 not yet assigned priority: Debian including 1 source packages (node-handlebars), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-23383
redhat medium — https://access.redhat.com/security/cve/CVE-2021-23383
ubuntu medium CVE-2021-23383 medium priority: Ubuntu including 1 source packages (node-handlebars), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 9, needs-triage 6, DNE 1. https://ubuntu.com/security/CVE-2021-23383

Affected software / configurations for CVE-2021-23383

Vendor Product Version Raw CPE
handlebarsjs handlebars < 4.7.7 cpe:2.3:a:handlebarsjs:handlebars:*:*:*:*:*:node.js:*:*
netapp e-series_performance_analyzer — cpe:2.3:a:netapp:e-series_performance_analyzer:-:*:*:*:*:*:*:*

References for CVE-2021-23383

cvelogic Threat Intelligence