Matrix Synap Synapse JSON denial of service

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CVSS Meta Temp Score
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CTI Interest Score
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5.6$0-$5k0.00

A vulnerability was found in Matrix Synap Synapse. It has been declared as problematic. Affected by this vulnerability is an unknown part of the component JSON Handler. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. As an impact it is known to affect availability. The summary by CVE is:

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.

The weakness was released 11/24/2020. The advisory is shared at github.com. This vulnerability is known as CVE-2020-26890 since 10/08/2020. The attack can be launched remotely. A single authentication is necessary for exploitation. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 1.20.0 eliminates this vulnerability.

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VulDB Meta Base Score: 5.9
VulDB Meta Temp Score: 5.6

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔒

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VulDB Base Score: 🔒
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VulDB Reliability: 🔍

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Exploitinginfoedit

Class: Denial of service
CWE: CWE-404
ATT&CK: T1499

Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

Price Prediction: 🔍
Current Price Estimation: 🔒

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Countermeasuresinfoedit

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Synap 1.20.0

Timelineinfoedit

10/08/2020 CVE assigned
11/24/2020 +47 days Advisory disclosed
11/24/2020 +0 days VulDB entry created
12/10/2020 +16 days VulDB last update

Sourcesinfoedit

Advisory: github.com
Status: Confirmed

CVE: CVE-2020-26890 (🔒)

Entryinfoedit

Created: 11/24/2020 10:35 AM
Updated: 12/10/2020 09:43 AM
Changes: (18) vulnerability_cvss3_nvd_av vulnerability_cvss3_nvd_ac vulnerability_cvss3_nvd_pr vulnerability_cvss3_nvd_ui vulnerability_cvss3_nvd_s vulnerability_cvss3_nvd_c vulnerability_cvss3_nvd_i vulnerability_cvss3_nvd_a vulnerability_cvss2_nvd_av vulnerability_cvss2_nvd_ac vulnerability_cvss2_nvd_au vulnerability_cvss2_nvd_ci vulnerability_cvss2_nvd_ii vulnerability_cvss2_nvd_ai vulnerability_cvss3_meta_basescore vulnerability_cvss3_meta_tempscore vulnerability_cvss2_nvd_basescore vulnerability_cvss3_nvd_basescore
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