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
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.

Affected Packages

(8 across 8 ecosystems)
Alpine:v3.21(1)
PackageVulnerable rangeFixed inDependents
expat—2.8.2-r0—
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
expat—2.8.2-r0—
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
expat—2.8.2-r0—
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
expat—2.8.2-r0—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
expat2.2.10-2 ... 2.8.2-1~deb13u1 (47 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
expat2.5.0-1, 2.5.0-1+deb12u1, 2.5.0-1+deb12u22.5.0-1+deb12u3—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
expat2.7.1-2 ... 2.8.1-1 (9 versions)2.8.2-1~deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
expat2.7.1-2 ... 2.8.2-1~deb13u1 (10 versions)2.8.2-1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 53× 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.

Showing the most recent 100 of 191 total refreshes for this CVE.

  1. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-10 09:35 UTCEPSS rescore
  3. 2026-09-08 22:01 UTCEPSS rescore
  4. 2026-09-07 16:01 UTCEPSS rescore
  5. 2026-09-06 13:47 UTCEPSS rescore
  6. 2026-09-02 14:12 UTCEPSS rescore
  7. 2026-09-01 13:54 UTCEPSS rescore
  8. 2026-09-01 04:40 UTCEPSS rescore
  9. 2026-08-30 20:41 UTCEG score recompute
  10. 2026-08-30 20:41 UTCVendor advisory
  11. 2026-08-30 20:41 UTCGHSA enrichment
  12. 2026-08-30 19:17 UTCEPSS rescore
  13. 2026-08-30 01:22 UTCEPSS rescore
  14. 2026-08-28 21:42 UTCEPSS rescore
  15. 2026-08-27 14:25 UTCEPSS rescore
  16. 2026-08-26 14:46 UTCEPSS rescore
  17. 2026-08-25 13:49 UTCEPSS rescore
  18. 2026-08-24 23:24 UTCEG score recompute
  19. 2026-08-24 23:24 UTCVendor advisory
  20. 2026-08-24 23:24 UTCGHSA enrichment
  21. 2026-08-23 23:16 UTCVendor advisory
  22. 2026-08-23 23:16 UTCGHSA enrichment
  23. 2026-08-22 22:54 UTCEG score recompute
  24. 2026-08-22 22:54 UTCVendor advisory
  25. 2026-08-22 22:54 UTCGHSA enrichment
Show 75 more
  1. 2026-08-21 23:49 UTCEPSS rescore
  2. 2026-08-21 08:08 UTCEG score recompute
  3. 2026-08-21 08:08 UTCVendor advisory
  4. 2026-08-21 08:08 UTCGHSA enrichment
  5. 2026-08-20 22:55 UTCEPSS rescore
  6. 2026-08-20 07:53 UTCEG score recompute
  7. 2026-08-20 07:53 UTCVendor advisory
  8. 2026-08-20 07:53 UTCGHSA enrichment
  9. 2026-08-19 17:04 UTCEPSS rescore
  10. 2026-08-19 05:47 UTCEG score recompute
  11. 2026-08-19 05:47 UTCVendor advisory
  12. 2026-08-19 05:47 UTCGHSA enrichment
  13. 2026-08-17 13:47 UTCEPSS rescore
  14. 2026-08-16 20:18 UTCEG score recompute
  15. 2026-08-16 20:18 UTCVendor advisory
  16. 2026-08-16 20:18 UTCGHSA enrichment
  17. 2026-08-16 14:56 UTCEPSS rescore
  18. 2026-08-16 02:14 UTCEPSS rescore
  19. 2026-08-15 19:23 UTCEG score recompute
  20. 2026-08-15 19:23 UTCVendor advisory
  21. 2026-08-15 19:23 UTCGHSA enrichment
  22. 2026-08-15 01:30 UTCEPSS rescore
  23. 2026-08-14 19:14 UTCEG score recompute
  24. 2026-08-14 19:14 UTCVendor advisory
  25. 2026-08-14 19:14 UTCGHSA enrichment
  26. 2026-08-13 22:00 UTCEPSS rescore
  27. 2026-08-13 19:06 UTCVendor advisory
  28. 2026-08-13 19:06 UTCGHSA enrichment
  29. 2026-08-12 18:58 UTCEG score recompute
  30. 2026-08-12 18:58 UTCVendor advisory
  31. 2026-08-12 18:58 UTCGHSA enrichment
  32. 2026-08-12 13:51 UTCEPSS rescore
  33. 2026-08-11 18:50 UTCEG score recompute
  34. 2026-08-11 18:50 UTCVendor advisory
  35. 2026-08-11 18:50 UTCGHSA enrichment
  36. 2026-08-11 00:00 UTCEPSS rescore
  37. 2026-08-10 18:42 UTCGHSA enrichment
  38. 2026-08-09 18:15 UTCEG score recompute
  39. 2026-08-09 18:15 UTCVendor advisory
  40. 2026-08-09 18:15 UTCGHSA enrichment
  41. 2026-08-09 13:46 UTCEPSS rescore
  42. 2026-08-08 18:07 UTCEG score recompute
  43. 2026-08-08 18:07 UTCVendor advisory
  44. 2026-08-08 18:07 UTCGHSA enrichment
  45. 2026-08-08 16:37 UTCEPSS rescore
  46. 2026-08-07 17:58 UTCEG score recompute
  47. 2026-08-07 17:58 UTCGHSA enrichment
  48. 2026-08-06 17:51 UTCEG score recompute
  49. 2026-08-06 17:51 UTCVendor advisory
  50. 2026-08-06 17:50 UTCGHSA enrichment
  51. 2026-08-06 13:47 UTCEPSS rescore
  52. 2026-08-05 19:17 UTCEPSS rescore
  53. 2026-08-05 17:40 UTCGHSA enrichment
  54. 2026-08-04 15:17 UTCEG score recompute
  55. 2026-08-04 15:17 UTCVendor advisory
  56. 2026-08-04 15:17 UTCGHSA enrichment
  57. 2026-08-04 15:10 UTCEPSS rescore
  58. 2026-08-04 10:39 UTCEPSS rescore
  59. 2026-08-03 10:36 UTCEPSS rescore
  60. 2026-08-03 08:00 UTCGHSA enrichment
  61. 2026-08-02 05:05 UTCEG score recompute
  62. 2026-08-02 05:05 UTCVendor advisory
  63. 2026-08-02 05:05 UTCGHSA enrichment
  64. 2026-08-02 02:27 UTCEPSS rescore
  65. 2026-08-01 04:56 UTCEG score recompute
  66. 2026-08-01 04:56 UTCVendor advisory
  67. 2026-08-01 04:56 UTCGHSA enrichment
  68. 2026-08-01 04:16 UTCEPSS rescore
  69. 2026-07-31 03:45 UTCEG score recompute
  70. 2026-07-31 03:45 UTCVendor advisory
  71. 2026-07-31 03:45 UTCGHSA enrichment
  72. 2026-07-30 16:28 UTCEPSS rescore
  73. 2026-07-30 02:48 UTCEG score recompute
  74. 2026-07-30 02:48 UTCVendor advisory
  75. 2026-07-30 02:48 UTCGHSA enrichment

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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