Security readout for executives and security teams
Plain-English summary
This is a low-severity denial-of-service issue in fast-xml-parser. Affected versions can crash with a stack overflow when XMLBuilder is used with preserveOrder:true. Business urgency is limited unless an externally reachable workflow builds XML from untrusted or poorly bounded input.
Executive priority
Handle in normal dependency maintenance unless the vulnerable builder path is externally reachable. Escalate only for services where malformed input could repeatedly crash production processes.
Technical view
fast-xml-parser before 5.3.8 can stack overflow in XMLBuilder when preserveOrder:true is enabled. The published CVSS 4.0 score is 2.7 with low availability impact and no stated confidentiality or integrity impact. Version 5.3.8 contains the fix.
Likely exposure
Exposure is most likely in Node.js applications using fast-xml-parser below 5.3.8, specifically XMLBuilder with preserveOrder:true. Risk increases where builder input is influenced by users, APIs, queues, or partner integrations.
Exploitation context
The bundle does not show CISA KEV listing or active exploitation evidence. The issue is a crash condition, not data theft or code execution based on the provided sources.
Researcher notes
The affected surface is XML building, not general XML parsing. Evidence in the bundle names a fixed version and workarounds, but does not provide proof of exploitation in the wild.
Mitigation direction
- Upgrade fast-xml-parser to version 5.3.8 or later.
- If upgrade is delayed, use XMLBuilder with preserveOrder:false.
- Check or constrain input data before passing it to XMLBuilder.
- Prioritize internet-facing or partner-facing XML generation paths.
Validation and detection
- Inventory applications depending on fast-xml-parser below 5.3.8.
- Review code for XMLBuilder configured with preserveOrder:true.
- Identify whether builder input can come from untrusted sources.
- Confirm deployed packages resolve to version 5.3.8 or later.
- Run regression tests for XML output after changing preserveOrder settings.
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
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ATT&CK lookup starting points
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CWE-120: Exact CWE lookup
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Open ATT&CK lookupCVE-2026-27942 mapping review
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Open ATT&CK lookup- Severity
- Low
- CVSS
- 2.7 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
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.
SSVC decision data
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U——GitHub_MVulnerability scoring details
Base CVSS 4.0 score
2.7LowVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-fj3w-jwp8-x2g3CVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/NaturalIntelligence/fast-xml-parser/pull/791CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/NaturalIntelligence/fast-xml-parser/commit/c13a961910f14986295dd28484eee830fa1a0e8aCVE reference, GitHub_M · 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.
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.