CVE-2026-48516

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Source
https://cve.org/CVERecord?id=CVE-2026-48516
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-48516.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-48516
Aliases
Published
2026-06-22T21:09:51.787Z
Modified
2026-07-08T08:12:34.912613031Z
Severity
  • 6.3 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N CVSS Calculator
Summary
MessagePack-CSharp: InterfaceLookupFormatter bypasses collision-resistant comparer settings
Details

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter<TKey,TElement> constructs an internal Dictionary<TKey, IGrouping<TKey,TElement>> with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer<TKey>(). This formatter omission allows hash-collision CPU denial of service against ILookup<TKey,TElement> even when the application has opted into the untrusted-data security posture This vulnerability is fixed in 2.5.301 and 3.1.7.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48516.json",
    "cwe_ids": [
        "CWE-407"
    ],
    "cna_assigner": "GitHub_M"
}
References

Affected packages

Git / github.com/messagepack-csharp/messagepack-csharp

Affected ranges

Type
GIT
Repo
https://github.com/messagepack-csharp/messagepack-csharp
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
5657b1e34ea2869a2ca6bc0aa6617158620201ba
Introduced
ff3af77f546138d9da71707baddf2c30f55dfc15
Fixed
1b53ae8b7681340199faf337bcbb0eb5aed702de
Database specific 
{
    "source": "CPE_RANGE",
    "cpe": "cpe:2.3:a:messagepack:messagepack:*:*:*:*:*:c\\#:*:*",
    "extracted_events": [
        {
            "introduced": "0"
        },
        {
            "fixed": "2.5.301"
        },
        {
            "introduced": "3.0.3"
        },
        {
            "fixed": "3.1.7"
        }
    ]
}

Affected versions

0.*
0.1.0-beta
0.2.0-beta
1.*
1.0.1
v1.*
v1.0.2
v1.0.3
v1.1.1
v1.1.2
v1.2.0
v1.2.1
v1.2.3
v1.3.0
v1.3.1
v1.3.2
v1.3.3
v1.4.0
v1.4.1
v1.4.2
v1.4.4
v1.5.0
v1.5.1
v1.6.0
v1.6.1
v1.6.1.2
v1.6.2
v1.7.0
v1.7.2
v1.7.3
v1.7.3.1
v1.7.3.2
v1.7.3.3
v1.7.3.4
v2.*
v2.0.110-alpha
v2.0.119-beta
v2.0.123-beta
v2.0.204-beta
v2.0.270-rc
v2.0.94-alpha
v2.1.115
v2.1.143
v2.1.152
v2.1.165
v2.1.194
v2.1.80
v2.1.90
v2.2.113
v2.2.60
v2.2.85
v2.3.75
v2.3.85
v2.4.23-alpha
v2.4.35
v2.4.59
v2.5.103
v2.5.108
v2.5.124
v2.5.129
v2.5.140
v2.5.168
v2.5.171
v2.5.172
v2.5.187
v2.5.192
v2.5.198
v2.5.94
v3.*
v3.0.3
v3.0.300
v3.0.301
v3.1.0
v3.1.1
v3.1.2
v3.1.3
v3.1.4
v3.1.5
v3.1.6

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-48516.json"