Skip to main content
VulnerabilityPublished

CVE-2026-48514: MessagePack-CSharp · Unity unsafe blit formatter allocates from unbounded byte length

Affects MessagePackSource GCVE Database

0
Compare

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

CVSS 4.0 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
NuGetMessagePackAffected
  • <2.5.301
Fixed in
  • 2.5.301
NuGetMessagePackAffected
  • >=3.0 <3.1.7
Fixed in
  • 3.1.7

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.

References

Community reviews

Loading reviews…