Security readout for executives and security teams
Plain-English summary
CVE-2026-25128 is a denial-of-service issue in the npm library fast-xml-parser. Applications using affected versions can crash when they parse untrusted XML containing out-of-range numeric entities. The issue affects availability, not confidentiality or integrity, and is fixed in version 5.3.4.
Executive priority
Treat as a high-priority availability risk for services that accept XML from outside trusted boundaries. Patch quickly for exposed applications, especially customer-facing APIs and integrations. Lower urgency may be reasonable for isolated internal tools with no untrusted XML input.
Technical view
fast-xml-parser versions 5.0.9 through 5.3.3 mishandle numeric entity processing for out-of-range code points. Parsing crafted XML can trigger an uncaught RangeError, terminating applications that do not safely handle the exception. The CVSS 3.1 score is 7.5, driven by network reachability, low complexity, no authentication, and high availability impact.
Likely exposure
Exposure is likely where Node.js applications or services use fast-xml-parser 5.0.9 through 5.3.3 to process XML from users, partners, APIs, queues, or uploaded files. Internal-only XML processing is lower risk unless attackers can influence that input path.
Exploitation context
The provided sources do not state active exploitation, and this CVE is not marked KEV. Exploitation requires the application to parse attacker-controlled XML with an affected library version and to lack protective exception handling or isolation around parser failures.
Researcher notes
Evidence is clear on affected versions, impact, CVSS, and fixed release. Public sources do not provide evidence of active exploitation. The root issue maps to improper input validation and uncaught exception handling during numeric entity parsing.
Mitigation direction
- Upgrade fast-xml-parser to version 5.3.4 or later.
- Inventory direct and transitive dependencies for affected fast-xml-parser versions.
- Prioritize internet-facing or partner-facing XML ingestion services.
- Review vendor advisory and release notes for implementation-specific guidance.
- Add defensive error handling around XML parsing where appropriate.
Validation and detection
- Check package manifests and lockfiles for fast-xml-parser versions 5.0.9 through 5.3.3.
- Identify services that parse XML from untrusted or external sources.
- Confirm deployed artifacts use fast-xml-parser 5.3.4 or later.
- Review application logs for parser RangeError crashes around XML ingestion.
- Verify dependency scanners recognize CVE-2026-25128 or GHSA-37qj-frw5-hhjh.
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-20: Exact CWE lookup
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Open ATT&CK lookupCWE-248: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-25128 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
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-37qj-frw5-hhjhCVE reference · x_refsource_CONFIRM
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/4e387f61c4a5cef792f6a2f42467013290bf95dcCVE reference · x_refsource_MISC
- https://github.com/NaturalIntelligence/fast-xml-parser/releases/tag/v5.3.4CVE reference · x_refsource_MISC
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 Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Uncaught Exception
Uncaught Exception represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.