CVE-2026-33349

MEDIUMPre-NVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 63% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: Elevated riskExposed: 0

A fix is available — apply it.

fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks. From version 4.0.0-beta.3 to before version 5.5.7, the DocTypeReader in fast-xml-parser uses JavaScript truthy checks to evaluate maxEntityCount and maxEntitySize configuration limits. When a developer explicitly sets either limit to 0 — intending to disallow all entities or restrict entity size to zero bytes — the falsy nature of 0 in JavaScript causes the guard conditions to short-circuit, completely bypassing the limits. An attacker who can supply XML input to such an application can trigger unbounded entity expansion, leading to memory exhaustion and denial of service. This issue has been patched in version 5.5.7.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
43(Track)
EG Risk 43/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity59% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
38%
KEV
Not listed

Published

March 24, 2026

Last Modified

June 17, 2026

Advisory Details (2)

Auto-updated Aug 4, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
github Patch Available🟡 PoC Available

Entity Expansion Limits Bypassed When Set to Zero Due to JavaScript Falsy Evaluation in fast-xml-parser · Advisory · NaturalIntelligence/fast-xml-parser · GitHub

https://github.com/NaturalIntelligence/fast-xml-parser/security/advisories/GHSA-jp2q-39xq-3w4g
github_commit Patch Available

commit 239b64aa1fc5 (NaturalIntelligence/fast-xml-parser)

Patch available: NaturalIntelligence/fast-xml-parser v5.5.7 (contains commit 239b64aa1fc5)

https://github.com/NaturalIntelligence/fast-xml-parser/commit/239b64aa1fc5c5455ddebbbb54a187eb68c9fdb7

Vendor Advisories for CVE-2026-33349(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatrhdh/rhdh-hub-rhel9:17809307402026-06-09redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
node-webfont11.4.0+dfsg2+~cs35.7.26-10 ... 11.4.0+dfsg2+~cs35.7.26-9 (14 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
node-webfont11.4.0+dfsg2+~cs35.7.26-13 ... 11.4.0+dfsg2+~cs35.7.26-21 (8 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
node-webfont11.4.0+dfsg2+~cs35.7.26-13 ... 11.4.0+dfsg2+~cs35.7.26-21 (8 versions)——
npm(1)
PackageVulnerable rangeFixed inDependents
fast-xml-parser—5.5.7—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 32× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-17 19:30 UTCEPSS rescore
  4. 2026-09-16 14:08 UTCEPSS rescore
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-15 03:11 UTCEPSS rescore
  7. 2026-09-13 16:47 UTCEPSS rescore
  8. 2026-09-12 15:01 UTCEPSS rescore
  9. 2026-09-11 14:53 UTCEPSS rescore
  10. 2026-09-11 09:37 UTCEPSS rescore
  11. 2026-09-10 09:34 UTCEPSS rescore
  12. 2026-09-08 22:00 UTCEPSS rescore
  13. 2026-09-07 16:01 UTCEPSS rescore
  14. 2026-09-06 13:47 UTCEPSS rescore
  15. 2026-09-06 13:47 UTCEPSS rescore
  16. 2026-09-04 05:06 UTCEPSS rescore
  17. 2026-09-02 15:08 UTCOSV refresh
  18. 2026-09-02 14:11 UTCEPSS rescore
  19. 2026-09-01 13:53 UTCEPSS rescore
  20. 2026-09-01 04:39 UTCEPSS rescore
  21. 2026-09-01 04:39 UTCEPSS rescore
  22. 2026-08-30 19:17 UTCEPSS rescore
  23. 2026-08-30 01:22 UTCEPSS rescore
  24. 2026-08-28 21:41 UTCEPSS rescore
  25. 2026-08-27 14:25 UTCEPSS rescore
Show 53 more
  1. 2026-08-26 14:46 UTCEPSS rescore
  2. 2026-08-25 13:49 UTCEPSS rescore
  3. 2026-08-24 14:17 UTCEPSS rescore
  4. 2026-08-23 00:19 UTCEPSS rescore
  5. 2026-08-21 23:49 UTCEPSS rescore
  6. 2026-08-20 22:55 UTCEPSS rescore
  7. 2026-08-20 22:55 UTCEPSS rescore
  8. 2026-08-19 17:03 UTCEPSS rescore
  9. 2026-08-18 13:48 UTCEPSS rescore
  10. 2026-08-17 13:47 UTCEPSS rescore
  11. 2026-08-16 14:56 UTCEPSS rescore
  12. 2026-08-16 10:31 UTCEG score recompute
  13. 2026-08-16 10:31 UTCVendor advisory
  14. 2026-08-16 02:14 UTCEPSS rescore
  15. 2026-08-15 01:30 UTCEPSS rescore
  16. 2026-08-14 06:49 UTCEG score recompute
  17. 2026-08-14 06:49 UTCVendor advisory
  18. 2026-08-13 22:00 UTCEPSS rescore
  19. 2026-08-12 23:51 UTCEG score recompute
  20. 2026-08-12 23:51 UTCVendor advisory
  21. 2026-08-12 13:50 UTCEPSS rescore
  22. 2026-08-12 01:59 UTCEG score recompute
  23. 2026-08-12 01:59 UTCVendor advisory
  24. 2026-08-11 04:08 UTCEG score recompute
  25. 2026-08-11 04:08 UTCVendor advisory
  26. 2026-08-11 00:00 UTCEPSS rescore
  27. 2026-08-10 04:25 UTCEG score recompute
  28. 2026-08-10 04:25 UTCVendor advisory
  29. 2026-08-09 13:46 UTCEPSS rescore
  30. 2026-08-09 06:25 UTCEG score recompute
  31. 2026-08-09 06:25 UTCVendor advisory
  32. 2026-08-08 16:37 UTCEPSS rescore
  33. 2026-08-07 16:44 UTCEG score recompute
  34. 2026-08-07 16:44 UTCVendor advisory
  35. 2026-08-06 13:46 UTCEPSS rescore
  36. 2026-08-06 01:10 UTCEG score recompute
  37. 2026-08-06 01:10 UTCVendor advisory
  38. 2026-08-05 19:17 UTCEPSS rescore
  39. 2026-08-04 15:10 UTCEPSS rescore
  40. 2026-08-04 10:38 UTCEPSS rescore
  41. 2026-08-03 23:54 UTCEG score recompute
  42. 2026-08-03 23:54 UTCVendor advisory
  43. 2026-08-03 10:36 UTCEPSS rescore
  44. 2026-08-02 15:43 UTCEG score recompute
  45. 2026-08-02 15:43 UTCVendor advisory
  46. 2026-08-02 02:27 UTCEPSS rescore
  47. 2026-08-01 04:16 UTCEPSS rescore
  48. 2026-07-30 16:28 UTCEPSS rescore
  49. 2026-07-30 01:30 UTCEPSS rescore
  50. 2026-07-27 14:13 UTCEPSS rescore
  51. 2026-07-27 12:50 UTCEG score recompute
  52. 2026-07-27 12:50 UTCVendor advisory
  53. 2026-07-27 12:50 UTCOSV refresh

Frequently asked(5)

What is CVE-2026-33349?
CVE-2026-33349 is a medium vulnerability published on March 24, 2026. fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks. From version 4.0.0-beta.3 to before version 5.5.7, the DocTypeReader in fast-xml-parser uses JavaScript truthy checks to evaluate maxEntityCount and maxEntitySize configuration limits. When a…
When was CVE-2026-33349 disclosed?
CVE-2026-33349 was first published in the National Vulnerability Database on March 24, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33349 actively exploited?
CVE-2026-33349 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 61.6% of all scored CVEs.
What is the CVSS score of CVE-2026-33349?
CVE-2026-33349 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-33349?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33349, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-33349

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