CVEs / CVE-2021-3156

CVE-2021-3156: Sudo Heap-Based Buffer Overflow Vulnerability

• Known exploited in the CISA KEV catalog since 6 Apr 2022
• high 7.8 CVSS 3.1 (NVD)
• EPSS 99.9% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
• Last changed at its sources 24 Oct 2026

Summary

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

Description

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.

Affected and fixed versions

Exploitation

Severity

References

• CVE-2021-3156 on NVD
• CVE-2021-3156 in the CISA KEV catalog
• CVE-2021-3156 on OSV
• http://packetstormsecurity.com/files/161160/Sudo-Heap-Based-Buffer-Overflow.html Exploit, Third Party Advisory, VDB Entry
• http://packetstormsecurity.com/files/161230/Sudo-Buffer-Overflow-Privilege-Escalation.html Exploit, Third Party Advisory, VDB Entry
• http://packetstormsecurity.com/files/161270/Sudo-1.9.5p1-Buffer-Overflow-Privilege-Escalation.html Exploit, Third Party Advisory, VDB Entry
• http://packetstormsecurity.com/files/161293/Sudo-1.8.31p2-1.9.5p1-Buffer-Overflow.html Exploit, Third Party Advisory, VDB Entry
• http://packetstormsecurity.com/files/176932/glibc-syslog-Heap-Based-Buffer-Overflow.html Exploit, Third Party Advisory, VDB Entry
• http://seclists.org/fulldisclosure/2021/Feb/42 Mailing List, Third Party Advisory
• http://seclists.org/fulldisclosure/2021/Jan/79 Exploit, Mailing List, Third Party Advisory
• http://seclists.org/fulldisclosure/2024/Feb/3 Exploit, Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/01/26/3 Exploit, Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/01/27/1 Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/01/27/2 Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/02/15/1 Exploit, Mailing List, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2021/09/14/2 Mailing List, Patch, Third Party Advisory
• http://www.openwall.com/lists/oss-security/2024/01/30/6 Exploit, Mailing List
• http://www.openwall.com/lists/oss-security/2024/01/30/8 Mailing List
• https://kc.mcafee.com/corporate/index?page=content&id=SB10348 Broken Link, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/01/msg00022.html Mailing List, Third Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CALA5FTXIQBRRYUA2ZQNJXB6OQMAXEII/ Mailing List, Release Notes
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LHXK6ICO5AYLGFK2TAX5MZKUXTUKWOJY/ Mailing List, Release Notes
• https://security.gentoo.org/glsa/202101-33 Third Party Advisory