{"id":"AZL-113024","summary":"CVE-2026-48511 affecting package python-msgpack 1.2.3-1","details":"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\u003cstring, object\u003e.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.","modified":"2026-11-13T06:04:48Z","published":"2026-06-22T22:16:47Z","upstream":["CVE-2026-48511"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48511"}],"affected":[{"package":{"name":"python-msgpack","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/python-msgpack"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"1.2.3-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-113024.json"}}],"schema_version":"1.9.2"}