HighCVE-2022-39248

    matrix-android-sdk2 vulnerable to Olm/Megolm protocol confusion (CVE-2022-39248)

    Published Sources: CVE.org, OSV

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    What is affected, what to do

    matrix-android-sdk2 is the Matrix SDK for Android. Prior to version 1.5.1, an attacker cooperating with a malicious homeserver can construct messages that legitimately appear to have come from another person, without any indication such as a grey shield.

    Update Matrix-org Matrix-android-sdk2 to version 1.5.1.

    Affected
    • Matrix-org Matrix-android-sdk2 lt *..1.5.1
    Fixed in
    • Matrix-org Matrix-android-sdk2 1.5.1

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

    Metrics

    8.6

    Priority

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

    Source: Vendor (CNA), CVSS v3

    8.6

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org, OSV

    1.0 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 62.7

    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
    75.90 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
    8.6 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
    8.6
    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
    1.0 %
    Moderate — model estimates 1-10% 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
    62.7
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    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
    CISA assessment (SSVC)
    Exploitation: none known · automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 23 April 2025
    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-322, CWE-287

    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

    matrix-android-sdk2 is the Matrix SDK for Android. Prior to version 1.5.1, an attacker cooperating with a malicious homeserver can construct messages that legitimately appear to have come from another person, without any indication such as a grey shield. Additionally, a sophisticated attacker cooperating with a malicious homeserver could employ this vulnerability to perform a targeted attack in order to send fake to-device messages appearing to originate from another user. This can allow, for example, to inject the key backup secret during a self-verification, to make a targeted device start using a malicious key backup spoofed by the homeserver. matrix-android-sdk2 would then additionally sign such a key backup with its device key, spilling trust over to other devices trusting the matrix-android-sdk2 device. These attacks are possible due to a protocol confusion vulnerability that accepts to-device messages encrypted with Megolm instead of Olm. matrix-android-sdk2 version 1.5.1 has been modified to only accept Olm-encrypted to-device messages and to stop signing backups on a successful decryption. Out of caution, several other checks have been audited or added. This attack requires coordination between a malicious home server and an attacker, so those who trust their home servers do not need a workaround.

    Source: NVD (NIST), OSV (Open Source Vulnerabilities), cvelistv5

    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
    matrix-orgmatrix-android-sdk2
    • < 1.5.1
    • 1.5.1
    matrixsoftware_development_kit
    • < 1.5.1
    • 1.5.1
    mavenorg.matrix.android:matrix-android-sdk2
    • 1.4.25
    • 1.4.2
    • 1.4.4
    • 1.2.2
    • 1.4.14
    • 1.4.16
    • 1.4.13
    • 1.3.8
    • 1.4.32
    • 1.3.10
    • 1.3.2
    • 1.3.18
    • 1.3.9
    • 1.4.11
    • 0.0.2
    • 1.3.13
    • 1.4.34
    • 1.2.1
    • 1.3.4
    • 1.3.7
    • 1.4.27
    • 1.3.14
    • 1.3.0
    • 1.4.36
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    Vendors and products

    Weakness classes (CWE)

    • CWE-322Key Exchange without Entity Authentication

      Base

      The product performs a key exchange with an actor without verifying the identity of that actor.

      Entry at MITRE CWE-322

    • CWE-287Improper Authentication

      Class

      When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

      Entry at MITRE CWE-287

    References & sources

    • github.commatrix-org/matrix-android-sdk2/security/advisories/GHSA-fpgf-pj…web, x_refsource_CONFIRM, Patch, Third-party advisory
    • NVD (NIST)vuln/detail/CVE-2022-39248advisory
    • github.commatrix-org/matrix-android-sdk2/commit/77df720a238d17308deab83ec…web, x_refsource_MISC, Patch, Third-party advisory
    • github.commatrix-org/matrix-android-sdk2package
    • github.commatrix-org/matrix-android-sdk2/releases/tag/v1.5.1web, x_refsource_MISC, Release notes, Third-party advisory
    • matrix.orgblog/2022/09/28/upgrade-now-to-address-encryption-vulns-in-matr…web, x_refsource_MISC, Vendor advisory
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