HighCVE-2026-62848

    Metalama: Deserialization of Untrusted Data (CVE-2026-62848)

    Published Last modified Sources: CVE.org

    What is affected, what to do

    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 available sources name no fixed version. Check the vendor guidance in the references below.

    Affected
    • Metalama gte 2023.0.101-rc, < 2025.1.18..*

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    7.3

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    7.3

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 8.3

    Show all metrics
    Severity
    High
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    67.05 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    7.3 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.3
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    0.2 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    8.3
    Low — this CVE sits in the lower 10% of all CVEs scored today.
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-502, CWE-913

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    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: cvelistv5, NVD (NIST)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    metalamaMetalama
    • ≥ 2023.0.101-rc, < 2025.1.18
    • —

    Weakness classes (CWE)

    • CWE-502Deserialization of Untrusted Data

      Base

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

      Entry at MITRE CWE-502

    • CWE-913Improper Control of Dynamically-Managed Code Resources

      Class

      The product does not properly restrict reading from or writing to dynamically-managed code resources such as variables, objects, classes, attributes, functions, or executable instructions or statements.

      Entry at MITRE CWE-913

    References & sources

    • github.commetalama/Metalama/commit/5b4ced29f2b25631cc2e44d05b0fd5fe838b6c…x_refsource_MISC
    • github.commetalama/Metalama/commit/d97f52e1b53ffe4176b2b05c56ffdf1ccd2f53…x_refsource_MISC
    • github.commetalama/Metalama/pull/1651x_refsource_MISC
    • github.commetalama/Metalama/releases/tag/release/2025.1.18x_refsource_MISC
    • github.commetalama/Metalama/releases/tag/release/2026.0.25x_refsource_MISC
    • github.commetalama/Metalama/releases/tag/release/2026.1.19x_refsource_MISC
    • github.commetalama/Metalama/security/advisories/GHSA-h26j-4vp7-x9w2x_refsource_CONFIRM

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. ReceivedGitHub

      CVSS V3.1: AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

      Weakness type: CWE-913, CWE-502

      Description added or changed

      Show 12 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      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.
      CVSSadded
      —
      AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
      Weakness type (CWE)added
      —
      CWE-913
      Weakness type (CWE)added
      —
      CWE-502
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/62xxx/CVE-2026-62848.json">CVE-2026-62848</a>
      Referenceadded
      —
      https://github.com/metalama/Metalama/commit/5b4ced29f2b25631cc2e44d05b0fd5fe838b6cbe
      Referenceadded
      —
      https://github.com/metalama/Metalama/commit/d97f52e1b53ffe4176b2b05c56ffdf1ccd2f53a9
      Referenceadded
      —
      https://github.com/metalama/Metalama/pull/1651
      Referenceadded
      —
      https://github.com/metalama/Metalama/releases/tag/release/2025.1.18
      Referenceadded
      —
      https://github.com/metalama/Metalama/releases/tag/release/2026.0.25
      Referenceadded
      —
      https://github.com/metalama/Metalama/releases/tag/release/2026.1.19
      Referenceadded
      —
      https://github.com/metalama/Metalama/security/advisories/GHSA-h26j-4vp7-x9w2

      Source identifier: security-advisories@github.com

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