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Sudo · Sudo

CVE-2021-3156

Sudo Heap-Based Buffer Overflow Vulnerability

CISA KEV record

CISA date added
2022-04-06
CISA due date
2022-04-27
Known ransomware use
Unknown

NVD risk context

7.8 HIGH

CVSS is a technical severity score. CISA’s KEV status remains the evidence that this vulnerability is known to be exploited.

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Attack vector
Local
An attacker needs local access to the affected system.
Attack complexity
Low
Exploitation does not require unusual conditions beyond normal attacker control.
Privileges required
Low
The attacker needs limited privileges before exploiting the issue.
User interaction
None
No action by another user is required.

Description

Sudo contains an off-by-one error that can result in a heap-based buffer overflow, which allows for privilege escalation.

Required action

Apply updates per vendor instructions.

NVD reference index

Vendor and remediation references

NVD has tagged these sources as vendor advisories, patches, mitigations, or release notes.

Other NVD references (28)

MITRE CWE context

CWE classification

CWE-122 Heap-based Buffer Overflow

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

View official MITRE CWE details ↗
CWE-193 Off-by-one Error

A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.

View official MITRE CWE details ↗

NVD record timing

NVD record timeline

These dates describe NVD’s record, not CISA’s KEV addition or remediation due date.

NVD published
Jan 26, 2021, 09:15 PM UTC
When NVD first published this CVE record.
NVD last updated
Jun 17, 2026, 04:04 AM UTC
When NVD last changed its analysis or record data.
Advanced: view the technical CVSS vector

This standardized code is intended for security tools and technical analysts. The plain-language risk summary above explains its main points.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

View NVD record ↗

CISA notes

https://nvd.nist.gov/vuln/detail/CVE-2021-3156