CyberSecBulletin
CVE-2026-62848NVD status: Deferred

Metalama: Deserialization of Untrusted Data

Published Updated By the CyberSecBulletin desk

CVE-2026-62848 is a high-severity deserialization of untrusted data vulnerability in Metalama, with a CVSS 3.1 base score of 7.3 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, but only if a user takes part, for example by opening a link or file. Affected Metalama versions: >= 2023.0.101-rc, < 2025.1.18; >= 2025.2.0-preview, <= 2025.2.5-rc; >= 2026.0.0-preview, < 2026.0.25, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.19% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Metalama you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
MetalamaMetalama>= 2023.0.101-rc, < 2025.1.18; >= 2025.2.0-preview, <= 2025.2.5-rc; >= 2026.0.0-preview, < 2026.0.25; >= 2026.1.0-preview, < 2026.1.19Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
RequiredA user must take an action such as opening a file or link.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H. Scored by CNA (github.com).

Official description

Metalama is a Roslyn-based open-source patterns and architecture toolkit for C#. From 2023.0.101-rc until 2025.1.18, 2026.0.25 and 2026.1.19, the Windows Visual Studio integration deserializes local named-pipe messages without restricting which CLR types can be instantiated. The pipe connects `devenv`, the out-of-process Roslyn code-analysis process and the `CodeLens` process, and has the predictable name `Metalama_{role}_{processId}_{hash(PackageVersion)}`. Releases from the first public 2023.0 line through 2026.0.x use Newtonsoft.Json with `TypeNameHandling.All`; the later `SerializationBinder` only remaps assembly names, and `BindToType` resolves arbitrary wire-supplied types without an allow-list. Releases 2026.1.0 through 2026.1.18 use typeless MessagePack with `TypelessObjectResolver` and likewise instantiate arbitrary types. A same-user local process able to write to the pipe can send crafted messages that lead to arbitrary code execution with confidentiality, integrity and availability impacts inside the affected Visual Studio process. Default Windows pipe ACLs limit writers to the same logged-in user, so this does not escalate privileges or cross a security boundary; command-line and MSBuild-only builds do not use the channel. The maintained Metalama + PostSharp extension is affected from 2024.1 through 2026.1.4, while earlier Metalama-free PostSharp versions are unaffected. The retired Metalama and Caravela extensions remain affected and require removal or migration. The framework issue is fixed in versions 2025.1.18, 2026.0.25 and 2026.1.19; the maintained Metalama + PostSharp Visual Studio extension is fixed in version 2026.1.5. The retired Metalama and Caravela extensions require removal or migration.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

How developers prevent this class of flaw

  • If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
  • When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
  • Explicitly define a final object() to prevent deserialization.

More Deserialization of Untrusted Data vulnerabilities (CWE-502)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Metalama

All Metalama vulnerabilities

Recent Deserialization of Untrusted Data vulnerabilities

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