CVE-2021-26562

CRITICALNVD 9.08.1▼

9.0

Out-of-bounds write vulnerability in synoagentregisterd in Synology DiskStation Manager (DSM) before 6.2.3-25426-3 allows man-in-the-middle attackers to execute arbitrary code via syno_finder_site HTTP header.

CVSS v3: 9.0
EG Score: 8.1(medium)
EPSS: 80.7%
KEV: Not listed

Published

February 26, 2021

Last Modified

January 14, 2025

References (4)

security@synologyhttps://www.synology.com/security/advisory/Synology_SA_20_26
security@synologyhttps://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1159
af854a3a-2127-422b-91ae-364da2661108https://www.synology.com/security/advisory/Synology_SA_20_26
af854a3a-2127-422b-91ae-364da2661108https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1159

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-787Out-of-bounds Write

Data Freshness Timeline

(refreshed 12× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

2026-06-08 14:15 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-07 15:23 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-06 13:46 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 22:45 UTCEPSS rescore
2026-06-05 06:09 UTCEPSS rescore
2026-06-05 06:09 UTCEPSS rescore
2026-06-04 13:10 UTCEPSS rescore
2026-06-04 13:10 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-02 20:11 UTCEPSS rescore
2026-06-01 13:50 UTCEPSS rescore
2026-06-01 13:50 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 22:29 UTCEPSS rescore
2026-05-31 00:15 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-26562?

CVE-2021-26562 is a critical vulnerability published on February 26, 2021. Out-of-bounds write vulnerability in synoagentregisterd in Synology DiskStation Manager (DSM) before 6.2.3-25426-3 allows man-in-the-middle attackers to execute arbitrary code via synofindersite HTTP header.

When was CVE-2021-26562 disclosed?

CVE-2021-26562 was first published in the National Vulnerability Database on February 26, 2021, with the most recent update on January 14, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-26562 actively exploited?

CVE-2021-26562 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 80.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-26562?

CVE-2021-26562 has a CVSS v3 base score of 9.0 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.1.

How do I remediate CVE-2021-26562?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-26562, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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CVE-2021-26562

📅 Published

🔄 Last Modified

🔗 References (4)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-26562?

🔗 Related CVEs(same CWE)

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Published

Last Modified

References (4)

Frequently asked(5)

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