CVE-2026-48513

Home/CVE/MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, runtime-generated union deserializers

CVE

↯ PDF report

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, runtime-generated union deserializers

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, runtime-generated union deserializers emitted by DynamicUnionResolver do not call MessagePackSecurity.DepthStep(ref reader) and do not decrement reader.Depth around recursive deserialization and skip paths. This means union deserialization does not consistently participate in the maximum object graph depth enforcement that protects other recursive formatter paths.

For unknown union keys, the emitted deserializer calls reader.Skip() on attacker-controlled data without an enclosing depth step. This vulnerability is fixed in 2.5.301 and 3.1.7.

Monitor

⚠ NVD has not scored this CVE yet - manual triage required (common for recent CVEs)

No Sigma yet — build one → YARA rules0

Look this up elsewhere - one-click external pivots

NVD CVE.org CISA Exploit-DB GitHub PoC VulnCheck KEV GreyNoise

▸ How to read a CVE - triage first, then detect and patch

This page is every public fact about CVE-2026-48513, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.

Triage: should I act now? Four signals, and they are not interchangeable:

CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked. EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal. CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score. Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.

How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.

Then what - two workflows:

Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits. PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.

Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).

◆

ATT&CK techniques

Techniques this CVE enables. Pills with a solid outline are high confidence - named directly in ATT&CK or Nuclei, or human-curated by CTID; the rest are inferred from the weakness type using MITRE's CVE Mapping Methodology and the CWE → CAPEC chain. Broad, generic-weakness guesses are filtered out. A small N× marks a technique that N independent sources agree on.

T1059 · Command and Scripting Interpreter

▤ Build a SIEM detection for these techniques

▤

CAPEC attack patterns

Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.

CAPEC-CAPEC-230 · Serialized Data with Nested Payloads CAPEC-CAPEC-231 · Oversized Serialized Data Payloads

⬡

Weakness Classification

CWE-674Uncontrolled Recursion

▤

Related CVEs

CVEs linked to this one by a shared weakness (CWE) or affected product - joins on data already in the engine, with the reason shown per row. Not a guess.

CVE-2007-1285 The Zend Engine in PHP 4.x before 4.4.7, and 5.x before 5.2.2, allows remote att... 1 same CWE-674 HIGH CVE-2007-3409 Net::DNS before 0.60, a Perl module, allows remote attackers to cause a denial o... same CWE-674 HIGH CVE-2016-3627 The xmlStringGetNodeList function in tree.c in libxml2 2.9.3 and earlier, when u... same CWE-674 HIGH CVE-2016-4425 Jansson 2.7 and earlier allows context-dependent attackers to cause a denial of ... same CWE-674 MEDIUM

🔗

References & Sources

Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.

https://github.com/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-wfr3-xj75-pfwh