CVE-2021-36088

CRITICALNVD 9.89.8—

9.8

Fluent Bit (aka fluent-bit) 1.7.0 through 1.7.4 has a double free in flb_free (called from flb_parser_json_do and flb_parser_do).

CVSS v3: 9.8
EG Score: 9.8(medium)
EPSS: 66.9%
KEV: Not listed

Published

July 1, 2021

Last Modified

November 21, 2024

References (8)

cve@mitrehttps://bugs.chromium.org/p/oss-fuzz/issues/detail?id=33750
cve@mitrehttps://github.com/fluent/fluent-bit/commit/22346a74c07ceb90296be872be2d53eb92252a54
cve@mitrehttps://github.com/fluent/fluent-bit/pull/3453
cve@mitrehttps://github.com/google/oss-fuzz-vulns/blob/main/vulns/fluent-bit/OSV-2021-702.yaml
af854a3a-2127-422b-91ae-364da2661108https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=33750
af854a3a-2127-422b-91ae-364da2661108https://github.com/fluent/fluent-bit/commit/22346a74c07ceb90296be872be2d53eb92252a54
af854a3a-2127-422b-91ae-364da2661108https://github.com/fluent/fluent-bit/pull/3453
af854a3a-2127-422b-91ae-364da2661108https://github.com/google/oss-fuzz-vulns/blob/main/vulns/fluent-bit/OSV-2021-702.yaml

Weakness Classification(1)

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

CWE-415Double Free

Data Freshness Timeline

(refreshed 12× in last 7d / 20× 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
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2026-05-27 13:39 UTCepss_batch
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2026-05-26 14:14 UTCEG score recompute
2026-05-26 14:14 UTCGHSA enrichment
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch

Frequently asked(5)

What is CVE-2021-36088?

CVE-2021-36088 is a critical vulnerability published on July 1, 2021. Fluent Bit (aka fluent-bit) 1.7.0 through 1.7.4 has a double free in flbfree (called from flbparserjsondo and flbparserdo).

When was CVE-2021-36088 disclosed?

CVE-2021-36088 was first published in the National Vulnerability Database on July 1, 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-2021-36088 actively exploited?

CVE-2021-36088 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 66.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-36088?

CVE-2021-36088 has a CVSS v3 base score of 9.8 (NVD).

How do I remediate CVE-2021-36088?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-36088, 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-2021-36088

📅 Published

🔄 Last Modified

🔗 References (8)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-36088?

🔗 Related CVEs(same CWE)

Same CWE

Published

Last Modified

References (8)

Frequently asked(5)

Related CVEs(same CWE)