Security readout for executives and security teams
Plain-English summary
MuJS versions 1.0.1 through 1.1.1 can mishandle floating-point exponent parsing, causing memory corruption. In systems that expose MuJS to untrusted input, this could affect confidentiality, integrity, and availability. The provided sources do not show active exploitation, but the CVSS score is critical.
Executive priority
Treat as high-priority if MuJS is embedded in internet-facing or untrusted-input processing software. If MuJS is absent, no action is needed beyond documenting the negative exposure finding.
Technical view
The flaw is a CWE-119 buffer overflow in Artifex MuJS. An integer overflow occurs when js_strtod() reads a floating-point exponent in jsdtoa.c, leading to a buffer overflow through pointer *d. The affected range is MuJS 1.0.1 to 1.1.1.
Likely exposure
Exposure is limited to software that directly uses or embeds affected MuJS versions. Risk is highest where MuJS processes untrusted JavaScript or numeric input from network-accessible workflows.
Exploitation context
CVE metadata rates this as network-exploitable with low attack complexity and no privileges or user interaction. The source bundle marks KEV as false and provides no evidence of active exploitation.
Researcher notes
The bundle identifies the vulnerable function and affected range, but does not provide affected downstream products, exploit evidence, or a named fixed release. Validation should focus on embedded copies and the upstream patch state.
Mitigation direction
- Inventory applications and packages that embed MuJS.
- Confirm whether MuJS versions 1.0.1 to 1.1.1 are present.
- Upgrade MuJS or apply the upstream fix referenced in the commit.
- Restrict untrusted input paths that reach MuJS until remediated.
- Check downstream vendor guidance for packaged or embedded copies.
Validation and detection
- Review dependency manifests and vendored source for MuJS.
- Search binaries or SBOMs for affected MuJS version strings.
- Verify jsdtoa.c includes the upstream correction from the referenced commit.
- Confirm exposed services do not pass untrusted data into affected MuJS.
- Run regression tests for JavaScript numeric parsing after updating.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-119: Exact CWE lookup
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Open ATT&CK lookupCVE-2021-33797 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/ccxvii/mujs/issues/148CVE reference
- https://github.com/ccxvii/mujs/commit/833b6f1672b4f2991a63c4d05318f0b84ef4d550CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Restriction of Operations within the Bounds of a Memory Buffer
Improper Restriction of Operations within the Bounds of a Memory Buffer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.