How severe is CVE-2021-29087?

CVE-2021-29087 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2021-29087 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-29087?

CVE-2021-29087 primarily affects Synology Diskstation Manager. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-29087?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-29087 published?

CVE-2021-29087 was published on 2021-06-23 and last updated on 2026-06-17.

CVE-2021-29087

CVE-2021-29087 is a high-severity vulnerability in Synology Diskstation Manager with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (70th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-22
Affected product: Synology Diskstation Manager
Published: 2021-06-23
Last modified: 2026-06-17

Description

Improper limitation of a pathname to a restricted directory ('Path Traversal') vulnerability in webapi component in Synology DiskStation Manager (DSM) before 6.2.3-25426-3 allows remote attackers to write arbitrary files via unspecified vectors.

Frequently asked questions

What is CVE-2021-29087?: Improper limitation of a pathname to a restricted directory ('Path Traversal') vulnerability in webapi component in Synology DiskStation Manager (DSM) before 6.2.3-25426-3 allows remote attackers to write arbitrary files via unspecified vectors.
How severe is CVE-2021-29087?: CVE-2021-29087 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2021-29087 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-29087?: CVE-2021-29087 primarily affects Synology Diskstation Manager. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-29087?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-29087 published?: CVE-2021-29087 was published on 2021-06-23 and last updated on 2026-06-17.

References

https://www.synology.com/security/advisory/Synology_SA_20_26

Affected products (2)

cpe:2.3:o:synology:diskstation_manager:*:*:*:*:*:*:*:*
cpe:2.3:o:synology:diskstation_manager_unified_controller:*:*:*:*:*:*:*:*

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