CVE-2026-48513 json
MessagePack-CSharp: DynamicUnionResolver generated deserializers miss depth enforcement
published 4mo ago modified 4mo ago also GHSA-wfr3-xj75-pfwh , EUVD-2026-38383
- cvss
- 7.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 35%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- nuget MessagePack 2.5.301, 3.1.7
- messagepack messagepack 2.5.301, 3.1.7
Is CVE-2026-48513 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
- Assessed
- 4mo ago
Exploit prediction
0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-11).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 6.3 | 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 |
| CNA | 4.0 | 6.3 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| nuget | MessagePack | <2.5.301 >=3.0, <3.1.7 |
2.5.301 3.1.7 |
Affected products
- MessagePack-CSharp MessagePack-CSharp
Classification
- Weakness
-
- CWE-674 Uncontrolled Recursion
References
-
github.com
/MessagePack-CSharp/MessagePack-CSharp/security/advisories/GHSA-wfr3-xj75-pfwh
web, mitigation, vendor-advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-48513
advisory
-
github.com
/MessagePack-CSharp/MessagePack-CSharp
package
Sources
- CVE List CVE-2026-48513
- GitHub Advisory GHSA-wfr3-xj75-pfwh
- NVD CVE-2026-48513
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