CVE-2026-48506

MessagePack-CSharp: MessagePackReader.Skip can recurse without enforcing maximum object graph depth

HIGH
7.5
CVSS Score
Published: June 22, 2026 at 09:17 PM UTC
Updated: June 23, 2026 at 07:34 PM UTC
2 products affected across 2 vendorsMessagepackMessagepack

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Severity
HIGH7.5
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, MessagePackReader.TrySkip() recursively descends into nested arrays and maps without incrementing the reader depth or calling the configured depth checks. This bypasses MessagePackSecurity.MaximumObjectGraphDepth, the library's documented protection against deeply nested object graphs. Many generated and dynamic formatters call reader.Skip() when they encounter unknown map keys, unknown array members, ignored fields, or data that should be skipped for forward compatibility. A deeply nested value in one of these skipped positions can therefore cause unbounded recursion and an uncatchable StackOverflowException. This vulnerability is fixed in 2.5.301 and 3.1.7.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.5.3013.0.3 ≤ v < 3.1.7
Affected range stops below 2.5.301, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.1.7, so it looks safe — our inference, not a vendor statement
v < 2.5.301v < 3.1.7
Affected range stops below 2.5.301, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.1.7, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-674

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