CVE-2026-56407

MEDIUMPre-NVD 6.96.9—
EchelonGraph scoreMEDIUM confidence

Score 6.9 from GitHub Security Advisory published 2026-06-21. a secondary CVSS source baseline 6.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
6.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.9Exploit: None knownExposed: 0

A fix is available — apply it.

libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity textLen.

CVSS v3
6.9
EG Score
6.9(medium)
EG Risk
36(Track)
EG Risk 36/100SSVC: 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
Severity69% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
4%
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-2026-56407] Cap entity `textLen` against signed integer overflow

Fix merged in libexpat/libexpat PR #1262 on 2026-06-03 — awaiting tagged release

https://github.com/libexpat/libexpat/pull/1262

Vendor Advisories for CVE-2026-56407(3)

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
redhatexpat-main-2.8.2-1.1.hum12026-07-15redhat

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

(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 / 60× 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 211 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. 2026-09-04 05:07 UTCEPSS rescore
  7. 2026-09-02 14:12 UTCEPSS rescore
  8. 2026-09-01 13:54 UTCEPSS rescore
  9. 2026-09-01 04:40 UTCEPSS rescore
  10. 2026-08-30 20:41 UTCEG score recompute
  11. 2026-08-30 20:41 UTCVendor advisory
  12. 2026-08-30 20:41 UTCGHSA enrichment
  13. 2026-08-30 19:17 UTCEPSS rescore
  14. 2026-08-30 01:22 UTCEPSS rescore
  15. 2026-08-28 21:42 UTCEPSS rescore
  16. 2026-08-27 14:25 UTCEPSS rescore
  17. 2026-08-26 14:46 UTCEPSS rescore
  18. 2026-08-25 13:49 UTCEPSS rescore
  19. 2026-08-24 22:15 UTCEG score recompute
  20. 2026-08-24 22:15 UTCVendor advisory
  21. 2026-08-24 22:15 UTCGHSA enrichment
  22. 2026-08-23 21:58 UTCEG score recompute
  23. 2026-08-23 21:58 UTCVendor advisory
  24. 2026-08-23 21:58 UTCGHSA enrichment
  25. 2026-08-23 00:19 UTCEPSS rescore
Show 75 more
  1. 2026-08-22 22:54 UTCEG score recompute
  2. 2026-08-22 22:54 UTCVendor advisory
  3. 2026-08-22 22:54 UTCGHSA enrichment
  4. 2026-08-21 23:49 UTCEPSS rescore
  5. 2026-08-21 07:20 UTCEG score recompute
  6. 2026-08-21 07:20 UTCVendor advisory
  7. 2026-08-21 07:20 UTCGHSA enrichment
  8. 2026-08-20 22:55 UTCEPSS rescore
  9. 2026-08-20 07:53 UTCEG score recompute
  10. 2026-08-20 07:53 UTCVendor advisory
  11. 2026-08-20 07:53 UTCGHSA enrichment
  12. 2026-08-19 17:04 UTCEPSS rescore
  13. 2026-08-19 05:47 UTCEG score recompute
  14. 2026-08-19 05:47 UTCVendor advisory
  15. 2026-08-19 05:47 UTCGHSA enrichment
  16. 2026-08-18 13:48 UTCEPSS rescore
  17. 2026-08-17 15:09 UTCEG score recompute
  18. 2026-08-17 15:09 UTCVendor advisory
  19. 2026-08-17 15:09 UTCGHSA enrichment
  20. 2026-08-17 13:47 UTCEPSS rescore
  21. 2026-08-16 16:02 UTCEG score recompute
  22. 2026-08-16 16:02 UTCVendor advisory
  23. 2026-08-16 16:02 UTCGHSA enrichment
  24. 2026-08-16 14:56 UTCEPSS rescore
  25. 2026-08-16 02:14 UTCEPSS rescore
  26. 2026-08-15 16:58 UTCEG score recompute
  27. 2026-08-15 16:58 UTCVendor advisory
  28. 2026-08-15 16:58 UTCGHSA enrichment
  29. 2026-08-15 01:30 UTCEPSS rescore
  30. 2026-08-14 17:52 UTCEG score recompute
  31. 2026-08-14 17:52 UTCVendor advisory
  32. 2026-08-14 17:52 UTCGHSA enrichment
  33. 2026-08-13 22:00 UTCEPSS rescore
  34. 2026-08-13 18:44 UTCVendor advisory
  35. 2026-08-13 18:44 UTCGHSA enrichment
  36. 2026-08-12 18:22 UTCEG score recompute
  37. 2026-08-12 18:22 UTCVendor advisory
  38. 2026-08-12 18:22 UTCGHSA enrichment
  39. 2026-08-12 13:51 UTCEPSS rescore
  40. 2026-08-11 19:10 UTCEG score recompute
  41. 2026-08-11 19:10 UTCVendor advisory
  42. 2026-08-11 19:10 UTCGHSA enrichment
  43. 2026-08-11 00:00 UTCEPSS rescore
  44. 2026-08-10 20:06 UTCVendor advisory
  45. 2026-08-10 20:06 UTCGHSA enrichment
  46. 2026-08-09 21:01 UTCEG score recompute
  47. 2026-08-09 21:01 UTCVendor advisory
  48. 2026-08-09 21:01 UTCGHSA enrichment
  49. 2026-08-09 13:46 UTCEPSS rescore
  50. 2026-08-08 21:57 UTCEG score recompute
  51. 2026-08-08 21:57 UTCVendor advisory
  52. 2026-08-08 21:57 UTCGHSA enrichment
  53. 2026-08-08 16:37 UTCEPSS rescore
  54. 2026-08-07 22:52 UTCVendor advisory
  55. 2026-08-07 22:52 UTCGHSA enrichment
  56. 2026-08-06 23:47 UTCEG score recompute
  57. 2026-08-06 23:47 UTCVendor advisory
  58. 2026-08-06 23:47 UTCGHSA enrichment
  59. 2026-08-06 13:47 UTCEPSS rescore
  60. 2026-08-06 00:43 UTCEG score recompute
  61. 2026-08-06 00:43 UTCVendor advisory
  62. 2026-08-06 00:43 UTCGHSA enrichment
  63. 2026-08-05 19:17 UTCEPSS rescore
  64. 2026-08-05 01:38 UTCEG score recompute
  65. 2026-08-05 01:38 UTCVendor advisory
  66. 2026-08-05 01:38 UTCGHSA enrichment
  67. 2026-08-04 15:10 UTCEPSS rescore
  68. 2026-08-04 10:39 UTCEPSS rescore
  69. 2026-08-04 02:14 UTCEG score recompute
  70. 2026-08-04 02:14 UTCVendor advisory
  71. 2026-08-04 02:14 UTCGHSA enrichment
  72. 2026-08-03 10:36 UTCEPSS rescore
  73. 2026-08-03 03:09 UTCVendor advisory
  74. 2026-08-03 03:09 UTCGHSA enrichment
  75. 2026-08-02 04:03 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-56407?
CVE-2026-56407 is a medium vulnerability published on June 21, 2026. libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity textLen.
When was CVE-2026-56407 disclosed?
CVE-2026-56407 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-2026-56407 actively exploited?
CVE-2026-56407 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 96.4% of all scored CVEs.
What is the CVSS score of CVE-2026-56407?
CVE-2026-56407 has a CVSS v3 base score of 6.9 (NVD).
How do I remediate CVE-2026-56407?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56407, 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.

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