CVE-2021-26556

HIGHNVD 7.87.8—

7.8

When Octopus Server is installed using a custom folder location, folder ACLs are not set correctly and could lead to an unprivileged user using DLL side-loading to gain privileged access.

CVSS v3: 7.8
EG Score: 7.8(medium)
EPSS: 18.5%
KEV: Not listed

Published

October 7, 2021

Last Modified

November 21, 2024

References (2)

security@octopushttps://advisories.octopus.com/adv/2021-01---Local-privilege-escalation-in-Octopus-Server-%28CVE-2021-26556%29.1733296189.html
af854a3a-2127-422b-91ae-364da2661108https://advisories.octopus.com/adv/2021-01---Local-privilege-escalation-in-Octopus-Server-%28CVE-2021-26556%29.1733296189.html

Weakness Classification(1)

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

CWE-426Untrusted Search Path

Data Freshness Timeline

(refreshed 11× in last 7d / 18× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 09:22 UTCEG score recompute
2026-05-26 09:22 UTCGHSA enrichment
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch

Frequently asked(5)

What is CVE-2021-26556?

CVE-2021-26556 is a high vulnerability published on October 7, 2021. When Octopus Server is installed using a custom folder location, folder ACLs are not set correctly and could lead to an unprivileged user using DLL side-loading to gain privileged access.

When was CVE-2021-26556 disclosed?

CVE-2021-26556 was first published in the National Vulnerability Database on October 7, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-26556 actively exploited?

CVE-2021-26556 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 18.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-26556?

CVE-2021-26556 has a CVSS v3 base score of 7.8 (NVD).

How do I remediate CVE-2021-26556?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-26556, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-26556

Explore →

Is Your Infrastructure Affected by CVE-2021-26556?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs

CVE-2021-26556

📅 Published

🔄 Last Modified

🔗 References (2)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-26556?

🔗 Related CVEs(same CWE)

Same CWE

Published

Last Modified

References (2)

Frequently asked(5)

Related CVEs(same CWE)