How severe is CVE-2021-26567?

CVE-2021-26567 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-26567 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26567?

CVE-2021-26567 primarily affects Synology Diskstation Manager. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-26567?

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-2021-26567 published?

CVE-2021-26567 was published on 2021-02-26 and last updated on 2026-06-17.

CVE-2021-26567

CVE-2021-26567 is a high-severity vulnerability in Synology Diskstation Manager with a CVSS 3.x base score of 7.8. 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-787.

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 6.5
EPSS exploit prediction: 1% (62nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Synology Diskstation Manager
Published: 2021-02-26
Last modified: 2026-06-17

Description

Stack-based buffer overflow vulnerability in frontend/main.c in faad2 before 2.2.7.1 allow local attackers to execute arbitrary code via filename and pathname options.

Frequently asked questions

What is CVE-2021-26567?: Stack-based buffer overflow vulnerability in frontend/main.c in faad2 before 2.2.7.1 allow local attackers to execute arbitrary code via filename and pathname options.
How severe is CVE-2021-26567?: CVE-2021-26567 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-26567 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26567?: CVE-2021-26567 primarily affects Synology Diskstation Manager. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-26567?: 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-2021-26567 published?: CVE-2021-26567 was published on 2021-02-26 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:o:synology:diskstation_manager:*:*:*:*:*:*:*:*
cpe:2.3:o:synology:vs960hd_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:synology:skynas_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:synology:diskstation_manager_unified_controller:3.0:*:*:*:*:*:*:*
cpe:2.3:a:faad2_project:faad2:*:*:*:*:*:*:*:*

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