CVE-2021-33797Public exploitNetwork attack vector

Interpreter crash via unchecked exponent accumulation

Published Apr 17, 2023 · Updated Feb 6, 2025

Buffer overflow in Artifex MuJS 1.0.1 through 1.1.1 allows attackers to crash the interpreter with a crafted numeric literal. The js_strtod function accumulates exponent digits in a signed integer without an overflow guard, and the wrapped value drives an out-of-bounds global read. Any path that parses attacker-controlled JavaScript reaches the flaw; public evidence demonstrates a crash, not arbitrary code execution.

CVSS severity9.8
Critical
EPSS probability0.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in Artifex MuJS 1.0.1 through 1.1.1 allows attackers to crash the interpreter with a crafted numeric literal. The js_strtod function accumulates exponent digits in a signed integer without an overflow guard, and the wrapped value drives an out-of-bounds global read. Any path that parses attacker-controlled JavaScript reaches the flaw; public evidence demonstrates a crash, not arbitrary code execution.

The record

CVE
CVE-2021-33797
Published
Apr 17, 2023
Updated
Feb 6, 2025
Vendor
Artifex Software, Inc.
Product
MuJS
Classifications
CWE-119, CWE-190, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 6, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=mujs in versions 1.0.1 to 1.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Artifex Software, Inc. · MuJSversion=mujs in versions 1.0.1 to 1.1.1

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-190Integer Overflow or Wraparound
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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