CVE-2021-28831

HIGHNVD 7.57.5—

7.5

decompress_gunzip.c in BusyBox through 1.32.1 mishandles the error bit on the huft_build result pointer, with a resultant invalid free or segmentation fault, via malformed gzip data.

CVSS v3: 7.5
EG Score: 7.5(medium)
EPSS: 77.5%
KEV: Not listed

Published

March 19, 2021

Last Modified

December 17, 2025

References (14)

cve@mitrehttps://git.busybox.net/busybox/commit/?id=f25d254dfd4243698c31a4f3153d4ac72aa9e9bd
cve@mitrehttps://lists.debian.org/debian-lts-announce/2021/04/msg00001.html
cve@mitrehttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3UDQGJRECXFS5EZVDH2OI45FMO436AC4/
cve@mitrehttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7ZIFKPRR32ZYA3WAA2NXFA3QHHOU6FJ/
cve@mitrehttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZASBW7QRRLY5V2R44MQ4QQM4CZIDHM2U/
cve@mitrehttps://security.gentoo.org/glsa/202105-09
af854a3a-2127-422b-91ae-364da2661108https://git.busybox.net/busybox/commit/?id=f25d254dfd4243698c31a4f3153d4ac72aa9e9bd
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2021/04/msg00001.html
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2025/01/msg00012.html
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3UDQGJRECXFS5EZVDH2OI45FMO436AC4/
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7ZIFKPRR32ZYA3WAA2NXFA3QHHOU6FJ/
af854a3a-2127-422b-91ae-364da2661108https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZASBW7QRRLY5V2R44MQ4QQM4CZIDHM2U/
af854a3a-2127-422b-91ae-364da2661108https://security.gentoo.org/glsa/202105-09
af854a3a-2127-422b-91ae-364da2661108https://security.netapp.com/advisory/ntap-20250509-0005/

Patch Availability(3)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
ubuntu	busybox-static (1:1.30.1-4ubuntu6.4) @ focal	2026-05-26	ubuntu
ubuntu	busybox-static (1:1.22.0-15ubuntu1.4+esm1) @ xenial	2026-05-26	ubuntu
ubuntu	udhcpd (1:1.22.0-15ubuntu1.4+esm2) @ xenial	2026-05-26	ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

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

CWE-755Improper Handling of Exceptional Conditions

All Vendor Advisories

(4)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 8× in last 7d / 8× 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 19:36 UTCEG score recompute
2026-05-26 19:36 UTCVendor advisory
2026-05-26 19:36 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-2021-28831?

CVE-2021-28831 is a high vulnerability published on March 19, 2021. decompressgunzip.c in BusyBox through 1.32.1 mishandles the error bit on the huftbuild result pointer, with a resultant invalid free or segmentation fault, via malformed gzip data.

When was CVE-2021-28831 disclosed?

CVE-2021-28831 was first published in the National Vulnerability Database on March 19, 2021, with the most recent update on December 17, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-28831 actively exploited?

CVE-2021-28831 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 77.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-28831?

CVE-2021-28831 has a CVSS v3 base score of 7.5 (NVD).

How do I remediate CVE-2021-28831?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-28831, 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-2021-28831

Explore →

Is Your Infrastructure Affected by CVE-2021-28831?

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CVE-2021-28831

Published

Last Modified

References (14)

Patch Availability(3)

Weakness Classification(1)

All Vendor Advisories

Data Freshness Timeline

Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-28831?

Same vendor

Same CWE

CVE-2021-28831

📅 Published

🔄 Last Modified

🔗 References (14)

Patch Availability(3)

Weakness Classification(1)

All Vendor Advisories

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-28831?

🔗 Related CVEs(same vendor + same CWE)

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Published

Last Modified

References (14)

Frequently asked(5)

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