CVE-2026-48514: MessagePack-CSharp · Unity unsafe blit formatter allocates from unbounded byte length
Affects MessagePackSource GCVE Database
Not known to be exploited · CVSS 6.3 Medium : upgrade to 2.5.301 when convenient.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.5.301, 3.1.7
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade MessagePack to 2.5.301; MessagePack to 3.1.7.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| NuGetMessagePack | Affected
| Fixed in
|
| NuGetMessagePack | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Patching is recommended once the coordinated patched versions of MessagePack.UnityClient and companion packages are released. The fix will validate the byteLength before allocation to prevent excessive memory allocation. If you cannot patch yet, do not use Unity blit resolvers (UnityBlitResolver or UnityBlitWithPrimitiveArrayResolver) on data received from untrusted peers. Instead, use safer resolvers or explicitly validate and size-limit messages before deserialization.
Description
MessagePack-CSharp's UnsafeBlitFormatterBase<T>.Deserialize method in Unity blit resolvers improperly allocates memory based on an attacker-controlled byte length without validating it against the actual payload size. This can lead to excessive memory allocation and potential out-of-memory exceptions or process termination on memory-constrained platforms when deserializing untrusted data. The vulnerability affects the MessagePack.UnityClient package and specific resolvers prior to patched versions. The issue is mitigated by upgrading to patched versions or avoiding use of vulnerable resolvers with untrusted input.