CVE-2026-56409

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

Score 6.5 from GitHub Security Advisory published 2026-06-21. a secondary CVSS source baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
34(Track)
EG Risk 34/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
3%
KEV
Not listed

Published

June 21, 2026

Last Modified

June 23, 2026

Advisory Details (1)

Auto-updated Jun 22, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
github_pr

[CVE-2026-56409] xmlwf: Protect output path join from integer overflow

Fix merged in libexpat/libexpat PR #1259 on 2026-06-01 — awaiting tagged release

https://github.com/libexpat/libexpat/pull/1259

Vendor Advisories for CVE-2026-56409(2)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 72× 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. 2026-07-29 01:25 UTCVendor advisory
  2. 2026-07-29 01:25 UTCGHSA enrichment
  3. 2026-07-27 17:59 UTCEG score recompute
  4. 2026-07-27 17:59 UTCVendor advisory
  5. 2026-07-27 17:59 UTCGHSA enrichment
  6. 2026-07-26 16:18 UTCEG score recompute
  7. 2026-07-26 16:18 UTCVendor advisory
  8. 2026-07-26 16:18 UTCGHSA enrichment
  9. 2026-07-25 14:18 UTCEPSS rescore
  10. 2026-07-24 14:18 UTCEPSS rescore
  11. 2026-07-23 14:18 UTCEPSS rescore
  12. 2026-07-23 03:20 UTCEG score recompute
  13. 2026-07-22 14:08 UTCEPSS rescore
  14. 2026-07-20 17:08 UTCEPSS rescore
  15. 2026-07-19 14:31 UTCEPSS rescore
  16. 2026-07-19 14:31 UTCEPSS rescore
  17. 2026-07-18 10:04 UTCEPSS rescore
  18. 2026-07-16 22:53 UTCVendor advisory
  19. 2026-07-16 22:53 UTCGHSA enrichment
  20. 2026-07-16 17:03 UTCEPSS rescore
  21. 2026-07-15 22:45 UTCVendor advisory
  22. 2026-07-15 22:45 UTCGHSA enrichment
  23. 2026-07-15 16:57 UTCEPSS rescore
  24. 2026-07-15 16:57 UTCEPSS rescore
  25. 2026-07-14 22:37 UTCVendor advisory
Show 64 more
  1. 2026-07-14 22:37 UTCGHSA enrichment
  2. 2026-07-13 22:31 UTCEPSS rescore
  3. 2026-07-13 22:29 UTCGHSA enrichment
  4. 2026-07-13 06:13 UTCEPSS rescore
  5. 2026-07-13 06:13 UTCEPSS rescore
  6. 2026-07-12 22:20 UTCVendor advisory
  7. 2026-07-12 22:20 UTCGHSA enrichment
  8. 2026-07-12 05:46 UTCEPSS rescore
  9. 2026-07-11 22:12 UTCVendor advisory
  10. 2026-07-11 22:12 UTCGHSA enrichment
  11. 2026-07-10 22:04 UTCVendor advisory
  12. 2026-07-10 22:03 UTCGHSA enrichment
  13. 2026-07-09 21:55 UTCVendor advisory
  14. 2026-07-09 21:55 UTCGHSA enrichment
  15. 2026-07-09 19:10 UTCEPSS rescore
  16. 2026-07-09 19:10 UTCEPSS rescore
  17. 2026-07-08 21:46 UTCVendor advisory
  18. 2026-07-08 21:46 UTCGHSA enrichment
  19. 2026-07-08 15:16 UTCEPSS rescore
  20. 2026-07-08 15:16 UTCEPSS rescore
  21. 2026-07-07 21:39 UTCVendor advisory
  22. 2026-07-07 21:39 UTCGHSA enrichment
  23. 2026-07-07 13:46 UTCEPSS rescore
  24. 2026-07-07 13:46 UTCEPSS rescore
  25. 2026-07-06 21:30 UTCVendor advisory
  26. 2026-07-06 21:30 UTCGHSA enrichment
  27. 2026-07-06 16:27 UTCEPSS rescore
  28. 2026-07-06 16:27 UTCEPSS rescore
  29. 2026-07-05 20:53 UTCVendor advisory
  30. 2026-07-05 20:53 UTCGHSA enrichment
  31. 2026-07-05 02:31 UTCEPSS rescore
  32. 2026-07-05 02:30 UTCEPSS rescore
  33. 2026-07-04 20:44 UTCVendor advisory
  34. 2026-07-04 20:44 UTCGHSA enrichment
  35. 2026-07-04 06:31 UTCEPSS rescore
  36. 2026-07-04 06:31 UTCEPSS rescore
  37. 2026-07-03 20:36 UTCVendor advisory
  38. 2026-07-03 20:35 UTCGHSA enrichment
  39. 2026-07-02 20:26 UTCVendor advisory
  40. 2026-07-02 20:26 UTCGHSA enrichment
  41. 2026-07-01 20:18 UTCVendor advisory
  42. 2026-07-01 20:18 UTCGHSA enrichment
  43. 2026-07-01 15:07 UTCEPSS rescore
  44. 2026-06-30 20:10 UTCVendor advisory
  45. 2026-06-30 20:10 UTCGHSA enrichment
  46. 2026-06-29 20:02 UTCGHSA enrichment
  47. 2026-06-29 14:06 UTCEPSS rescore
  48. 2026-06-28 19:54 UTCGHSA enrichment
  49. 2026-06-28 14:07 UTCEPSS rescore
  50. 2026-06-28 04:56 UTCEPSS rescore
  51. 2026-06-28 04:56 UTCEPSS rescore
  52. 2026-06-27 19:46 UTCGHSA enrichment
  53. 2026-06-27 03:08 UTCEPSS rescore
  54. 2026-06-26 19:37 UTCGHSA enrichment
  55. 2026-06-25 19:29 UTCGHSA enrichment
  56. 2026-06-25 13:49 UTCEPSS rescore
  57. 2026-06-24 19:21 UTCGHSA enrichment
  58. 2026-06-24 14:05 UTCEPSS rescore
  59. 2026-06-23 21:33 UTCEPSS rescore
  60. 2026-06-23 21:33 UTCEPSS rescore
  61. 2026-06-23 19:09 UTCGHSA enrichment
  62. 2026-06-22 19:01 UTCGHSA enrichment
  63. 2026-06-21 18:45 UTCEG score recompute
  64. 2026-06-21 18:45 UTCGHSA enrichment

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-56409?
CVE-2026-56409 is a medium vulnerability published on June 21, 2026. xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used.
When was CVE-2026-56409 disclosed?
CVE-2026-56409 was first published in the National Vulnerability Database on June 21, 2026, with the most recent update on June 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56409 actively exploited?
CVE-2026-56409 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 96.7% of all scored CVEs.
What is the CVSS score of CVE-2026-56409?
CVE-2026-56409 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-56409?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56409, 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

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