CVE-2021-3156

HIGHNVD 7.89.0▲

7.8

Sudo before 1.9.5p2 contains an off-by-one error that can result in a heap-based buffer overflow, which allows privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character.

CVSS v3: 7.8
EG Score: 9.0(high)
EPSS: 99.8%
KEV: ⚠ Exploited

Published

January 26, 2021

Last Modified

November 10, 2025

References (68)

Patch Availability(14)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
ubuntu	sudo (1.8.9p5-1ubuntu1.5+esm6) @ trusty	2026-05-26	ubuntu
ubuntu	sudo-ldap (1.8.16-0ubuntu1.10) @ xenial	2026-05-26	ubuntu
redhat	redhat-virtualization-host-0:4.4.4-20210201.0.el8_3	2021-02-03	redhat
redhat	redhat-virtualization-host-0:4.3.13-20210127.0.el7_9	2021-02-03	redhat
redhat	sudo-0:1.8.23-3.el7_6.2	2021-01-27	redhat
redhat	sudo-0:1.8.23-10.el7_9.1	2021-01-27	redhat
redhat	sudo-0:1.8.19p2-12.el7_4.2	2021-01-26	redhat
redhat	sudo-0:1.8.23-4.el7_7.3	2021-01-26	redhat
redhat	sudo-0:1.8.29-6.el8_3.1	2021-01-26	redhat
redhat	sudo-0:1.8.29-5.el8_2.1	2021-01-26	redhat
redhat	sudo-0:1.8.6p3-29.el6_10.4	2021-01-26	redhat
redhat	sudo-0:1.8.6p7-17.el7_2.3	2021-01-26	redhat
redhat	sudo-0:1.8.6p7-23.el7_3.3	2021-01-26	redhat
redhat	sudo-0:1.8.25p1-8.el8_1.2	2021-01-26	redhat

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(2)

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

All Vendor Advisories

(14)

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 6× in last 7d / 6× 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 19:15 UTCEG score recompute
2026-05-26 19:15 UTCVendor advisory
2026-05-26 19:15 UTCGHSA enrichment
2026-05-26 19:13 UTCkev_newly_listed

Frequently asked(6)

What is CVE-2021-3156?

CVE-2021-3156 is a high vulnerability published on January 26, 2021. Sudo before 1.9.5p2 contains an off-by-one error that can result in a heap-based buffer overflow, which allows privilege escalation to root via "sudoedit -s" and a command-line argument that ends with a single backslash character.

When was CVE-2021-3156 disclosed?

CVE-2021-3156 was first published in the National Vulnerability Database on January 26, 2021, with the most recent update on November 10, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-3156 actively exploited?

Yes. CISA added CVE-2021-3156 to the Known Exploited Vulnerabilities catalog on April 6, 2022, affecting Sudo Sudo. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.

What is the CVSS score of CVE-2021-3156?

CVE-2021-3156 has a CVSS v3 base score of 7.8 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.

Which products are affected by CVE-2021-3156?

CVE-2021-3156 affects Sudo Sudo. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.

How do I remediate CVE-2021-3156?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-3156, 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-2021-3156

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CVE-2021-3156

Published

Last Modified

References (68)

Patch Availability(14)

Weakness Classification(2)

All Vendor Advisories

Data Freshness Timeline

Frequently asked(6)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-3156?

Same vendor

Same CWE

CVE-2021-3156

📅 Published

🔄 Last Modified

🔗 References (68)

Patch Availability(14)

Weakness Classification(2)

All Vendor Advisories

Data Freshness Timeline

❓ Frequently asked(6)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-3156?

🔗 Related CVEs(same vendor + same CWE)

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Last Modified

References (68)

Frequently asked(6)

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