CVE-2021-40511

HIGHNVD 7.57.5—

7.5

OBDA systems’ Mastro 1.0 is vulnerable to XML Entity Expansion (aka “billion laughs”) attack allowing denial of service.

CVSS v3: 7.5
EG Score: 7.5(medium)
EPSS: 64.7%
KEV: Not listed

Published

June 21, 2022

Last Modified

November 21, 2024

References (4)

cve@mitrehttps://www.cyberiskvision.com/advisory/
cve@mitrehttps://www.obdasystems.com/mastro
af854a3a-2127-422b-91ae-364da2661108https://www.cyberiskvision.com/advisory/
af854a3a-2127-422b-91ae-364da2661108https://www.obdasystems.com/mastro

Weakness Classification(1)

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

CWE-776Improper Restriction of Recursive Entity References (XML Entity Expansion)

Data Freshness Timeline

(refreshed 9× in last 7d / 9× 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.

2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 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 07:17 UTCepss_batch
2026-05-25 20:05 UTCEG score recompute
2026-05-25 20:05 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2021-40511?

CVE-2021-40511 is a high vulnerability published on June 21, 2022. OBDA systems’ Mastro 1.0 is vulnerable to XML Entity Expansion (aka “billion laughs”) attack allowing denial of service.

When was CVE-2021-40511 disclosed?

CVE-2021-40511 was first published in the National Vulnerability Database on June 21, 2022, 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-2021-40511 actively exploited?

CVE-2021-40511 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 64.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-40511?

CVE-2021-40511 has a CVSS v3 base score of 7.5 (NVD).

How do I remediate CVE-2021-40511?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-40511, 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-2021-40511

Explore →

Is Your Infrastructure Affected by CVE-2021-40511?

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

Start Free Scan →Browse All CVEs

CVE-2021-40511

📅 Published

🔄 Last Modified

🔗 References (4)