CVE-2021-31439

Name: CVE-2021-31439
Creator: NVD / NIST
Published: 2021-05-21T15:15:07.707+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 2.33%

Last modified Jun 17, 2026

CVE-2021-31439 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of Synology DiskStation Manager. Authentication is not required to exploit this vulnerablity. EPSS estimates a 2.33% chance of exploitation in the next 30 days.

Description

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of Synology DiskStation Manager. Authentication is not required to exploit this vulnerablity. The specific flaw exists within the processing of DSI structures in Netatalk. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a heap-based buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-12326.

Metrics

CVSS 3.1

8.8/10

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

EPSS Probability

2.33%

81.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Synology	Diskstation Manager	>= 6.2, < 6.2.3-25426-3
Debian	Debian Linux	10.0
Debian	Debian Linux	11.0
Netatalk	Netatalk	< 3.1.13

References

https://lists.debian.org/debian-lts-announce/2023/05/msg00018.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202311-02Issue Tracking, Third Party Advisory
https://www.debian.org/security/2023/dsa-5503Third Party Advisory
https://www.synology.com/zh-hk/security/advisory/Synology_SA_20_26Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-21-492/Third Party Advisory, VDB Entry
https://lists.debian.org/debian-lts-announce/2023/05/msg00018.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202311-02Issue Tracking, Third Party Advisory
https://www.debian.org/security/2023/dsa-5503Third Party Advisory
https://www.synology.com/zh-hk/security/advisory/Synology_SA_20_26Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-21-492/Third Party Advisory, VDB Entry

Timeline

Published: May 21, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-31439?

How severe is CVE-2021-31439?

CVE-2021-31439 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 2.33% probability of exploitation in the next 30 days.

How do I fix CVE-2021-31439?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-31439?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST