What is the CVSS score of CVE-2021-21404?

CVE-2021-21404 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 2.0%.

Is there a patch available for CVE-2021-21404?

Yes, a patch is available for CVE-2021-21404. Update the affected software to the latest version immediately.

Syncthing CVE-2021-21404

HIGH

Improper Input Validation (CWE-20)

2021-04-06 security-advisories@github.com

Denial Of Service Syncthing

7.5

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

CVE Published

Apr 06, 2021 - 20:15 nvd

HIGH 7.5

DescriptionNVD

Syncthing is a continuous file synchronization program. In Syncthing before version 1.15.0, the relay server strelaysrv can be caused to crash and exit by sending a relay message with a negative length field. Similarly, Syncthing itself can crash for the same reason if given a malformed message from a malicious relay server when attempting to join the relay. Relay joins are essentially random (from a subset of low latency relays) and Syncthing will by default restart when crashing, at which point it's likely to pick another non-malicious relay. This flaw is fixed in version 1.15.0.

AnalysisAI

Syncthing is a continuous file synchronization program. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity.

Technical ContextAI

This vulnerability is classified under CWE-20. Syncthing is a continuous file synchronization program. In Syncthing before version 1.15.0, the relay server strelaysrv can be caused to crash and exit by sending a relay message with a negative length field. Similarly, Syncthing itself can crash for the same reason if given a malformed message from a malicious relay server when attempting to join the relay. Relay joins are essentially random (from a subset of low latency relays) and Syncthing will by default restart when crashing, at which point it's likely to pick another non-malicious relay. This flaw is fixed in version 1.15.0. Affected products include: Syncthing. Version information: version 1.15.0.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.