Sudo Heap-Based Buffer Overflow Vulnerability

Exploited · KEV 2022-04-06Metasploit moduleCVE-2021-3156CWE-122CWE-193

Exploited since 2022-04-06. No WAF vendor names it yet. 1 public exploit repo.

Edge rules

0/8

Our test

No exploit yet

CVSS

7.8

EPSS

100.0% Top 0.1%

Posts, 14d

Published

2021-01-26

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.

Edge coverage

Claimed by vendors

CloudflareBefore feed historyOlder than its feed AWSNo public claimNot named Microsoft AzureNo public claimNot named Google CloudBefore feed historyOlder than its feed FastlyBefore feed historyOlder than its feed F5Before feed historyOlder than its feed AkamaiNo public sourceNo public changelog OWASP CRSBefore feed historyOlder than its feed

Ask Vigil

AI · answers from this page

Ask about CVE-2021-3156: who's covered, what to patch first, how vendors compare. I cite sources and won't help with attacks.

Workers AI (Llama 3.3). Can be wrong: check the cited source.

Severity, decoded

CVSS 3.1

7.8High

High · 7.8 / 10

Exploitable with local access, with low privileges and no user interaction, leading to full loss of confidentiality, integrity and availability.

Needs local accessAny user loginNo user actionWorks reliablyFull compromise

How the score is built8 metrics

Attack vectorAn attacker needs local access, or must trick a user into opening something on the machine.
Local
Attack complexityNo special conditions are needed; the attack works reliably.
Low
Privileges requiredThe attacker needs an ordinary user account.
Low
User interactionNo one has to click or open anything; the attack works on its own.
None
ScopeThe damage stays within the vulnerable component.
Unchanged
Confidentiality impactAn attacker can read all data the affected component holds, or the most sensitive parts of it.
High
Integrity impactAn attacker can change any data or files the affected component protects.
High
Availability impactAn attacker can take the component down completely or keep it from serving anyone.
High

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

CISA's assessmentSSVC, from the CVE record

ExploitationActive

Attackers are exploiting this in the wild.

AutomatableNo

At least one step needs hands-on work, which slows mass attacks.

Technical impactTotal

A successful attack gives full control over the affected software or all of its data.

Public exploits

4 found

1 Metasploit2 Exploit-DB0 Scanner template1 GitHub PoCs

MetasploitSudo Heap-Based Buffer Overflow2021-01-26 · exploit · rank Excellent · has check
Exploit-DBSudo 1.9.5p1 - 'Baron Samedit ' Heap-Based Buffer Overflow Privilege Escalation (1)2021-02-03 · local · multiple
Exploit-DBSudo 1.9.5p1 - 'Baron Samedit ' Heap-Based Buffer Overflow Privilege Escalation (2)2021-02-03 · local · multiple

Links are to third-party code: never run it outside an isolated lab.

Timeline

2021-01-26
CVE published
CVE List
2021-01-26
Metasploit module published
Sudo Heap-Based Buffer Overflow
2021-02-03
Exploit published on Exploit-DB
Sudo 1.9.5p1 - 'Baron Samedit ' Heap-Based Buffer Overflow Privilege Escalation (1)
2022-04-06
Added to CISA KEV
Confirmed exploitation in the wild
2026-11-02
First public exploit repository
AmroYasserH/DFIR-CVE-2021-3156-Incident-Response: DFIR investigation of SSH brute force attack and privilege escalation via CVE-2021-3156.
2026-11-02
First social mention we saw