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

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

• Documented patch — www.openwall.com (NIST National Vulnerability Database)
• Documented patch — www.oracle.com (NIST National Vulnerability Database)
• Documented patch — www.oracle.com (NIST National Vulnerability Database)
• Documented patch — www.oracle.com (NIST National Vulnerability Database)

CISA required action CISA

Apply updates per vendor instructions.

US federal deadline: Apr 27, 2022 — passed 1632 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

1. Identify exposed assets running the affected vendor/product/version combinations (Beyondtrust Privilege Management For Mac, Beyondtrust Privilege Management For Unix/linux, Debian Debian Linux…).
2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
3. Apply the fixed version or the patch documented under Remediation.
4. EPSS ahead of 100% of scored CVEs: prioritize it in the patch queue.
5. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-193

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 99.96%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

• Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
• Hunt retroactively in logs from before Apr 6, 2022 (KEV listing): exploitation may have started earlier.

Timeline

What happened to this CVE, newest first.

• 2026
• Fix documented
  Oct 13, 2026 · NIST National Vulnerability Database
• Affected products added · sudo project/sudo, fedoraproject/fedora, debian/debian linux, netapp/active iq unified manager, netapp/cloud backup, net
  Oct 13, 2026 · NIST National Vulnerability Database
• Source status changed · Published → Analyzed
  Oct 13, 2026 · NIST National Vulnerability Database
• Record published
  Oct 13, 2026
• CVSS changed · 7.8
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Source status changed · → Published
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• SSVC assessment updated
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Added to CISA KEV (detected)
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• Record created in this database
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• 2022
• Added to CISA KEV catalog
  Apr 5, 2022 · CISA
• 2021
• CVE published
  Jan 26, 2021 · mitre

Source activity

Repeated readings are counted rather than listed.

• 3× References added · Oct 13, 2026 – Oct 13, 2026
• 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

43 on the record

• www.oracle.com//security-alerts/cpujul2021.html
  Patch, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• www.oracle.com/security-alerts/cpuoct2021.html
  Patch, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• www.oracle.com/security-alerts/cpuapr2022.html
  Patch, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• www.openwall.com/lists/oss-security/2021/09/14/2
  mailing-list, Mailing List, Patch, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• www.cisa.gov/known-exploited-vulnerabilities-catalog
  US Government Resource, NIST National Vulnerability Database
• www.openwall.com/lists/oss-security/2024/01/30/8
  mailing-list, Mailing List, CVE Program (cve.org) e CISA ADP
• www.openwall.com/lists/oss-security/2021/01/27/2
  mailing-list, Mailing List, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• www.debian.org/security/2021/dsa-4839
  vendor-advisory, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• packetstormsecurity.com/files/161230/Sudo-Buffer-Overflow-Privilege-Escalation.html
  Exploit, Third Party Advisory, VDB Entry, CVE Program (cve.org) e CISA ADP
• www.kb.cert.org/vuls/id/794544
  third-party-advisory, Third Party Advisory, US Government Resource, CVE Program (cve.org) e CISA ADP
• www.openwall.com/lists/oss-security/2021/02/15/1
  mailing-list, Exploit, Mailing List, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sudo-privesc-j
  vendor-advisory, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• www.openwall.com/lists/oss-security/2024/01/30/6
  mailing-list, Exploit, Mailing List, CVE Program (cve.org) e CISA ADP
• lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/CALA5F
  GitHub Security Advisories
• security.netapp.com/advisory/ntap-20210128-0002/
  Third Party Advisory, CVE Program (cve.org) e CISA ADP
• packetstormsecurity.com/files/161293/Sudo-1.8.31p2-1.9.5p1-Buffer-Overflow.html
  Exploit, Third Party Advisory, VDB Entry, CVE Program (cve.org) e CISA ADP
• packetstormsecurity.com/files/161270/Sudo-1.9.5p1-Buffer-Overflow-Privilege-Escalation.html
  Exploit, Third Party Advisory, VDB Entry, CVE Program (cve.org) e CISA ADP
• lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LHXK
  GitHub Security Advisories
• security.gentoo.org/glsa/202101-33
  vendor-advisory, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• www.sudo.ws/stable.html
  Release Notes, CVE Program (cve.org) e CISA ADP
• www.openwall.com/lists/oss-security/2021/01/27/1
  mailing-list, Mailing List, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• seclists.org/fulldisclosure/2021/Feb/42
  mailing-list, Mailing List, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• github.com/advisories/GHSA-w5vh-2923-gp5c
  GitHub Security Advisories
• seclists.org/fulldisclosure/2021/Jan/79
  mailing-list, Exploit, Mailing List, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• nvd.nist.gov/vuln/detail/CVE-2021-3156
  GitHub Security Advisories
• lists.debian.org/debian-lts-announce/2021/01/msg00022.html
  mailing-list, Mailing List, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CALA
  GitHub Security Advisories
• security.netapp.com/advisory/ntap-20210128-0001/
  Third Party Advisory, CVE Program (cve.org) e CISA ADP
• security.netapp.com/advisory/ntap-20210128-0001
  GitHub Security Advisories
• www.beyondtrust.com/blog/entry/security-advisory-privilege-management-for-unix-linux-pmul
  Third Party Advisory, CVE Program (cve.org) e CISA ADP
• support.apple.com/kb/HT212177
  Third Party Advisory, CVE Program (cve.org) e CISA ADP
• packetstormsecurity.com/files/176932/glibc-syslog-Heap-Based-Buffer-Overflow.html
  Exploit, Third Party Advisory, VDB Entry, CVE Program (cve.org) e CISA ADP
• www.vicarius.io/vsociety/posts/sudoedit-pwned-cve-2021-3156
  Exploit, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• www.openwall.com/lists/oss-security/2021/01/26/3
  Exploit, Mailing List, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LHXK
  vendor-advisory, Mailing List, Release Notes, CVE Program (cve.org) e CISA ADP
• seclists.org/fulldisclosure/2024/Feb/3
  mailing-list, Exploit, Mailing List, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• packetstormsecurity.com/files/161160/Sudo-Heap-Based-Buffer-Overflow.html
  Exploit, Third Party Advisory, VDB Entry, CVE Program (cve.org) e CISA ADP
• kc.mcafee.com/corporate/index
  Broken Link, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• www.synology.com/security/advisory/Synology_SA_21_02
  Third Party Advisory, CVE Program (cve.org) e CISA ADP
• lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LHXK6I
  GitHub Security Advisories
• www.openwall.com/lists/oss-security/2021/01/26/3
  mailing-list, Exploit, Mailing List, Third Party Advisory, CVE Program (cve.org) e CISA ADP
• security.netapp.com/advisory/ntap-20210128-0002
  GitHub Security Advisories
• lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CALA
  vendor-advisory, Mailing List, Release Notes, CVE Program (cve.org) e CISA ADP

Elsewhere on this site

Related CVEs (same products)

• High CVE-2026-12996 A use-after-free in OpenVPN 2.6.0 through 2.6.20 and 2.7_alpha1 through 2.7.4 allows remote... Jul 30, 2026
• Medium CVE-2026-56968 Use of Uninitialized Resource in Gnu Sasl Jun 23, 2026
• Medium CVE-2026-54231 Abrt: unsanitized systemd journal content written to dump directory files enables content injection Jun 13, 2026
• High CVE-2026-54230 Abrt: event handler scripts follow symlinks when writing output files, allowing arbitrary file overwrites Jun 13, 2026
• High CVE-2026-49975 Apache HTTP Server: mod_http2 denial of service Jun 8, 2026
• Critical CVE-2025-13392 Improper Check for Unusual or Exceptional Conditions in Synology Diskstation Manager May 27, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

• No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
• No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
• No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2021-3156 is "Sudo Heap-Based Buffer Overflow Vulnerability", rated High. It affects Privilege Management For Mac (Beyondtrust); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 7.8 describes technical severity. EPSS 99.96% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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