CVE-2026-48511

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 86% 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, nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.5Exploit: NoneExposed: 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, ExpandoObjectFormatter.Deserialize populates System.Dynamic.ExpandoObject by calling IDictionary.Add for each map entry. ExpandoObject internally maintains member names in array-like structures, so inserting many distinct keys can require repeated linear scans and array copies. For large attacker-controlled maps, this produces quadratic CPU and allocation behavior. The issue is especially surprising because ExpandoObjectResolver.Options is configured with MessagePackSecurity.UntrustedData, but collision-resistant dictionary comparers cannot protect ExpandoObject insertion internals. This vulnerability is fixed in 2.5.301 and 3.1.7.

CVSS v3
7.5
EG Score
7.5(medium)
EPSS
13.9%
KEV
Not listed

Published

June 22, 2026

Last Modified

June 25, 2026

Advisory Details (1)

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

ExpandoObject formatter can perform quadratic insertion work on untrusted maps · Advisory · MessagePack-CSharp/MessagePack-CSharp · GitHub

https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-2x83-8g95-xh59

Vendor Advisories for CVE-2026-48511(1)

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 19× in last 7d / 47× 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. 2026-07-07 04:01 UTCEG score recompute
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 15:48 UTCEG score recompute
  4. 2026-07-06 03:32 UTCEG score recompute
  5. 2026-07-06 02:23 UTCEPSS rescore
  6. 2026-07-05 15:14 UTCEG score recompute
  7. 2026-07-05 03:03 UTCEG score recompute
  8. 2026-07-05 02:30 UTCEPSS rescore
  9. 2026-07-04 14:51 UTCEG score recompute
  10. 2026-07-04 06:31 UTCEPSS rescore
  11. 2026-07-04 02:40 UTCEG score recompute
  12. 2026-07-03 14:21 UTCEG score recompute
  13. 2026-07-03 02:11 UTCEG score recompute
  14. 2026-07-02 14:00 UTCEG score recompute
  15. 2026-07-02 01:49 UTCEG score recompute
  16. 2026-07-01 15:07 UTCEPSS rescore
  17. 2026-07-01 13:37 UTCEG score recompute
  18. 2026-07-01 01:26 UTCEG score recompute
  19. 2026-06-30 13:09 UTCEG score recompute
  20. 2026-06-30 00:58 UTCEG score recompute
  21. 2026-06-29 14:06 UTCEPSS rescore
  22. 2026-06-29 14:06 UTCEPSS rescore
  23. 2026-06-29 12:47 UTCEG score recompute
  24. 2026-06-29 00:36 UTCEG score recompute
  25. 2026-06-28 14:07 UTCEPSS rescore
Show 22 more
  1. 2026-06-28 12:24 UTCEG score recompute
  2. 2026-06-28 04:56 UTCEPSS rescore
  3. 2026-06-28 04:56 UTCEPSS rescore
  4. 2026-06-28 00:13 UTCEG score recompute
  5. 2026-06-27 12:01 UTCEG score recompute
  6. 2026-06-27 03:08 UTCEPSS rescore
  7. 2026-06-26 23:49 UTCEG score recompute
  8. 2026-06-26 11:38 UTCEG score recompute
  9. 2026-06-25 23:28 UTCEG score recompute
  10. 2026-06-25 17:48 UTCNVD updateCVSS v3 → 7.5 · severity → HIGH
  11. 2026-06-25 15:46 UTCMITRE cvelistV5CVSS v3 → 6.3 · severity → MEDIUM
  12. 2026-06-25 13:49 UTCEPSS rescore
  13. 2026-06-25 11:17 UTCEG score recompute
  14. 2026-06-24 23:06 UTCEG score recompute
  15. 2026-06-24 14:05 UTCEPSS rescore
  16. 2026-06-24 10:56 UTCEG score recompute
  17. 2026-06-23 22:44 UTCEG score recompute▲ 1.20
  18. 2026-06-23 21:33 UTCEPSS rescore
  19. 2026-06-23 21:33 UTCEPSS rescore
  20. 2026-06-23 17:33 UTCNVD updateCVSS v3 → 7.5 · severity → HIGH
  21. 2026-06-23 00:01 UTCEG score recompute
  22. 2026-06-23 00:00 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-48511?
CVE-2026-48511 is a high vulnerability published on June 22, 2026. MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, ExpandoObjectFormatter.Deserialize populates System.Dynamic.ExpandoObject by calling IDictionary<string, object>.Add for each map entry. ExpandoObject internally maintains member names in array-like structures, so…
When was CVE-2026-48511 disclosed?
CVE-2026-48511 was first published in the National Vulnerability Database on June 22, 2026, with the most recent update on June 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-48511 actively exploited?
CVE-2026-48511 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 13.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-48511?
CVE-2026-48511 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-48511?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-48511, 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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