CVE Feed

    Dashboard / CVE / CVE-2020-26890

    CVE-2020-26890

    Matrix Synapse before 1.20.0 erroneously permits non-standard NaN, Infinity, and -Infinity JSON values in fields of m.room.member events, allowing remote attackers to execute a denial of service attack against the federation and common Matrix clients. If such a malformed event is accepted into the room's state, the impact is long-lasting and is not fixed by an upgrade to a newer version, requiring the event to be manually redacted instead. Since events are replicated to servers of other room members, the impact is not constrained to the server of the event sender.

    Published:Nov 24, 2020
    Last Modified:Nov 21, 2024
    EPS:Nov 24, 2020
    EPSS Score:0.00955
    CVSS Score:7.5

    Affected Products

    Vendor
    Fedoraproject
    Product
    Fedora
    Vendor
    Matrix
    Product
    Synapse

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-20 Improper Input Validation

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-10 Buffer Overflow via Environment Variables
    CAPEC-101 Server Side Include (SSI) Injection
    CAPEC-104 Cross Zone Scripting
    CAPEC-108 Command Line Execution through SQL Injection
    CAPEC-109 Object Relational Mapping Injection
    CAPEC-110 SQL Injection through SOAP Parameter Tampering
    CAPEC-120 Double Encoding
    CAPEC-13 Subverting Environment Variable Values
    CAPEC-135 Format String Injection
    CAPEC-136 LDAP Injection
    CAPEC-14 Client-side Injection-induced Buffer Overflow
    CAPEC-153 Input Data Manipulation
    CAPEC-182 Flash Injection
    CAPEC-209 XSS Using MIME Type Mismatch
    CAPEC-22 Exploiting Trust in Client
    CAPEC-23 File Content Injection
    CAPEC-230 Serialized Data with Nested Payloads
    CAPEC-231 Oversized Serialized Data Payloads
    CAPEC-24 Filter Failure through Buffer Overflow
    CAPEC-250 XML Injection
    CAPEC-261 Fuzzing for garnering other adjacent user/sensitive data
    CAPEC-267 Leverage Alternate Encoding
    CAPEC-28 Fuzzing
    CAPEC-3 Using Leading 'Ghost' Character Sequences to Bypass Input Filters
    CAPEC-31 Accessing/Intercepting/Modifying HTTP Cookies
    CAPEC-42 MIME Conversion
    CAPEC-43 Exploiting Multiple Input Interpretation Layers
    CAPEC-45 Buffer Overflow via Symbolic Links
    CAPEC-46 Overflow Variables and Tags
    CAPEC-47 Buffer Overflow via Parameter Expansion
    CAPEC-473 Signature Spoof
    CAPEC-52 Embedding NULL Bytes
    CAPEC-53 Postfix, Null Terminate, and Backslash
    CAPEC-588 DOM-Based XSS
    CAPEC-63 Cross-Site Scripting (XSS)
    CAPEC-64 Using Slashes and URL Encoding Combined to Bypass Validation Logic
    CAPEC-664 Server Side Request Forgery
    CAPEC-67 String Format Overflow in syslog()
    CAPEC-7 Blind SQL Injection
    CAPEC-71 Using Unicode Encoding to Bypass Validation Logic
    CAPEC-72 URL Encoding
    CAPEC-73 User-Controlled Filename
    CAPEC-78 Using Escaped Slashes in Alternate Encoding
    CAPEC-79 Using Slashes in Alternate Encoding
    CAPEC-8 Buffer Overflow in an API Call
    CAPEC-80 Using UTF-8 Encoding to Bypass Validation Logic
    CAPEC-81 Web Server Logs Tampering
    CAPEC-83 XPath Injection
    CAPEC-85 AJAX Footprinting
    CAPEC-88 OS Command Injection
    CAPEC-9 Buffer Overflow in Local Command-Line Utilities

    Related CVEs

    CVE-2026-54231 (CVSS 5.5) — A content injection vulnerability was found in the ABRT post-create event handler scripts in libreport. The ev…
    CVE-2026-54230 (CVSS 7) — A symlink following vulnerability was found in the ABRT post-create event handler scripts in libreport. Event …
    CVE-2026-35094 (CVSS 3.3) — A flaw was found in libinput. An attacker capable of deploying a Lua plugin file in specific system directorie…
    CVE-2026-35093 (CVSS 8.8) — A flaw was found in libinput. A local attacker who can place a specially crafted Lua bytecode file in certain …
    CVE-2024-3056 (CVSS 7.7) — A flaw was found in Podman. This issue may allow an attacker to create a specially crafted container that, whe…
    CVE-2024-6293 (CVSS 8.8) — Use after free in Dawn in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentially explo…
    CVE-2024-6292 (CVSS 8.8) — Use after free in Dawn in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentially explo…
    CVE-2024-6291 (CVSS 8.8) — Use after free in Swiftshader in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentiall…
    CVE-2024-6290 (CVSS 8.8) — Use after free in Dawn in Google Chrome prior to 126.0.6478.126 allowed a remote attacker to potentially explo…
    CVE-2024-38277 (CVSS 5.4) — A unique key should be generated for a user's QR login key and their auto-login key, so the same key cannot be…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High