CVE-2026-48109

HIGHPre-NVD 8.28.2—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 58% 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
8.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 8.2Exploit: None knownExposed: 0

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

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, A vulnerability exists in the optional LZ4 decompression path used by MessagePack compression modes Lz4Block and Lz4BlockArray. The decoder implementation is based on a deprecated fast-decompression algorithm that does not take a source-length bound. A remote attacker can send a crafted MessagePack payload with manipulated LZ4 token/length fields to force out-of-bounds reads from the compressed input buffer. In affected environments, this can trigger an AccessViolationException during decompression, causing process termination (denial of service). Under some conditions, limited unintended memory disclosure from over-read data may also be possible before failure. This vulnerability is fixed in 2.5.301 and 3.1.7.

CVSS v3
8.2
EG Score
8.2(medium)
EG Risk
52(Track)
EG Risk 52/100SSVC: 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
Severity82% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
42%
KEV
Not listed

Published

June 11, 2026

Last Modified

June 23, 2026

Advisory Details (1)

Auto-updated Jun 23, 2026
Patch available. Sources: github.
github Patch Available

LZ4 decompression may fail with AccessViolationException after dereferencing memory from bad input · Advisory · MessagePack-CSharp/MessagePack-CSharp · GitHub

https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-hv8m-jj95-wg3x

Vendor Advisories for CVE-2026-48109(1)

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

Affected Packages

(1 across 1 ecosystem)
NuGet(1)
PackageVulnerable rangeFixed inDependents
MessagePack3.0.300 ... 3.1.6 (9 versions)3.1.7—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 26× 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 110 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-48109?
CVE-2026-48109 is a high vulnerability published on June 11, 2026. MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, A vulnerability exists in the optional LZ4 decompression path used by MessagePack compression modes Lz4Block and Lz4BlockArray. The decoder implementation is based on a deprecated fast-decompression algorithm that…
When was CVE-2026-48109 disclosed?
CVE-2026-48109 was first published in the National Vulnerability Database on June 11, 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-2026-48109 actively exploited?
CVE-2026-48109 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 57.6% of all scored CVEs.
What is the CVSS score of CVE-2026-48109?
CVE-2026-48109 has a CVSS v3 base score of 8.2 (NVD).
How do I remediate CVE-2026-48109?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-48109, 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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