Vulnerability in fast-xml-parser (CVE-2026-73569)
Summary
Vulnerability in fast-xml-parser (CVE-2026-73569). Risk of unauthorized operations or information disclosure. Exploitable via processEntity. Mitigation: upgrade to 5.10.1 or later.
Original description
The description as published by the source.
Impact
fast-xml-parser processes multiple "DOCTYPE" declarations within a single XML document. Each declaration passes its entities to @nodable/entities through addInputEntities().
addInputEntities() resets the entity expansion counters every time it is called. An attacker can therefore insert additional DOCTYPE declarations to repeatedly reset maxTotalExpansions and maxExpandedLength during one parse operation.
This allows a crafted XML document to exceed the configured entity-expansion limits and can cause excessive CPU use, event-loop blocking, memory exhaustion, and process termination.
Workarounds
- Manually check if multiple DOCTYPEs are not present in input contents
- Update to v5.10.1
- Keep
processEntityflag off
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-73569 has been found in fast-xml-parser.
Attackers can target a specific entry point like processEntity over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade fast-xml-parser to 5.10.1 or later.
If unsure, ask your IT team or search "fast-xml-parser CVE-2026-73569" on the vendor's site.
CVE-2026-73569 (fast-xml-parser) — CWE-776
Attack surface: processEntity
Patched: 5.10.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-776) exists in fast-xml-parser. Attackers reach the vulnerable code path via processEntity.
Check the vendor advisory for the affected versions of fast-xml-parser. Attack surface: processEntity.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 5.10.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'fast-xml-parser' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'fast-xml-parser' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
fast-xml-parserを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade fast-xml-parser to 5.10.1ステージング環境で 5.10.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。