CVE-2021-31439

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.

Published: 2021-05-21 Last update: 2025-01-14 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-31439 is rated Moderate Risk (62.8/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.03%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-31439

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-04 0.43% 1.03% +0.61%
2 2026-03-01 1.03% 0.43% -0.61%
3 2026-02-04 — 1.03% —

Full EPSS history (51 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-31439

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]
8.8 3.0 HIGH
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]
5.8 2.0 MEDIUM
AV:A/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:A)
Requires access to an adjacent network segment.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 6.5 6.4 [email protected]

Weakness enumeration for CVE-2021-31439

OS Trackers for CVE-2021-31439

vendor priority summary link
alpine — CVE-2021-31439: 1 source package rows (netatalk); 7 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2021-31439
debian not yet assigned CVE-2021-31439 not yet assigned priority: Debian including 1 source packages (netatalk), 4 status rows across 4 suites (bullseye, forky, sid, trixie): resolved 4. https://security-tracker.debian.org/tracker/CVE-2021-31439
gentoo high CVE-2021-31439: 1 GLSA(s) (202311-02), 1 atom(s) (net-fs/netatalk); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-31439
suse critical CVE-2021-31439 severity critical: SUSE including 3 source package names (libatalk12-3.1.0-3.8.1, netatalk-3.1.0-3.8.1, netatalk-devel-3.1.0-3.8.1), 5 product×package rows across 2 product lines (SUSE Linux Enterprise Software Development Kit 12 SP5, SUSE Linux Enterprise Workstation Extension 12 SP5): Fixed 5. https://www.suse.com/security/cve/CVE-2021-31439/
ubuntu medium CVE-2021-31439 medium priority: Ubuntu including 1 source packages (netatalk), 9 status rows across 9 suites (bionic, focal, impish, jammy, kinetic, lunar, trusty, upstream, xenial): not-affected 5, released 3, ignored 1. https://ubuntu.com/security/CVE-2021-31439

Affected software / configurations for CVE-2021-31439

Vendor Product Version Raw CPE
synology diskstation_manager >= 6.2, < 6.2.3-25426-3 cpe:2.3:o:synology:diskstation_manager:*:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
netatalk netatalk < 3.1.13 cpe:2.3:a:netatalk:netatalk:*:*:*:*:*:*:*:*

References for CVE-2021-31439

cvelogic Threat Intelligence