CVE-2021-4026

MEDIUMNVD 4.34.3—

4.3

bookstack is vulnerable to Improper Access Control

CVSS v3: 4.3
EG Score: 4.3(medium)
EPSS: 44.0%
KEV: Not listed

Published

November 30, 2021

Last Modified

November 21, 2024

References (4)

security@huntrhttps://github.com/bookstackapp/bookstack/commit/b4fa82e3298a15443ca40bff205b7a16a1031d92
security@huntrhttps://huntr.dev/bounties/c6dfa80d-43e6-4b49-95af-cc031bb66b1d
af854a3a-2127-422b-91ae-364da2661108https://github.com/bookstackapp/bookstack/commit/b4fa82e3298a15443ca40bff205b7a16a1031d92
af854a3a-2127-422b-91ae-364da2661108https://huntr.dev/bounties/c6dfa80d-43e6-4b49-95af-cc031bb66b1d

Affected Packages

(1 across 1 ecosystem)

Packagist(1)

Package	Vulnerable range	Fixed in	Dependents
ssddanbrown/bookstack	0.7.2 ... v21.11.1 (131 versions)	21.11.2	—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 17× 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
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 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 13:43 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:02 UTCEG score recompute

Frequently asked(5)

What is CVE-2021-4026?

CVE-2021-4026 is a medium vulnerability published on November 30, 2021. bookstack is vulnerable to Improper Access Control

When was CVE-2021-4026 disclosed?

CVE-2021-4026 was first published in the National Vulnerability Database on November 30, 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-2021-4026 actively exploited?

CVE-2021-4026 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 44.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-4026?

CVE-2021-4026 has a CVSS v3 base score of 4.3 (NVD).

How do I remediate CVE-2021-4026?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-4026, 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-2021-4026

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CVE-2021-4026

📅 Published

🔄 Last Modified

🔗 References (4)

Affected Packages

Weakness Classification(2)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-4026?

🔗 Related CVEs(same CWE)

Same CWE

Published

Last Modified

References (4)

Frequently asked(5)

Related CVEs(same CWE)