CVE-2021-3156

CRITICALNVD 7.89.0▲
EchelonGraph scoreHIGH confidence

Score elevated to 9.0 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2022-04-06), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 7.8 retained for reference. Confidence: HIGH.

Triggered by: CISA KEV (actively exploited)
Sources: cisa_kev, epss, ghsa, nvd
Trending — 5 sources updated this weekExploited in the wild
9.0EG
EchelonGraph verdictPatch nowTreat as an emergency — this is being exploited.
  • Actively exploited in the wild (CISA-KEV)
CISA-KEV: ExploitedEPSS PROB: 99%CVSS: 7.8Exploit: cisa kev · ssvc active · Metasploit · epss top5pct · epss high · public exploitExposed: 0

A fix is available — apply it.

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)
EG Risk
81(Attend)
EG Risk 81/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity90% × 45%
Exploitation100% × 40%
Automatability0% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
99%
EPSS %ILE
100%
KEV
⚠ Exploited

Published

January 26, 2021

Last Modified

November 10, 2025

Advisory Details (8)

Auto-updated Jun 4, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic

oss-security - Re: Baron Samedit: Heap-based buffer overflow in Sudo (CVE-2021-3156)

http://www.openwall.com/lists/oss-security/2021/01/27/1
generic

oss-security - Baron Samedit: Heap-based buffer overflow in Sudo (CVE-2021-3156)

http://www.openwall.com/lists/oss-security/2021/01/26/3
generic🟡 PoC Available

Full Disclosure: CVE-2023-6246: Heap-based buffer overflow in the glibc's syslog()

http://seclists.org/fulldisclosure/2024/Feb/3
generic

Full Disclosure: Baron Samedit: Heap-based buffer overflow in Sudo (CVE-2021-3156)

http://seclists.org/fulldisclosure/2021/Jan/79
generic

Full Disclosure: APPLE-SA-2021-02-09-1 macOS Big Sur 11.2.1, macOS Catalina 10.15.7 Supplemental Update, and macOS Mojave 10.14.6 Security Update 2021-002

http://seclists.org/fulldisclosure/2021/Feb/42
generic

Packet Storm

http://packetstormsecurity.com/files/176932/glibc-syslog-Heap-Based-Buffer-Overflow.html
generic

Packet Storm

http://packetstormsecurity.com/files/161230/Sudo-Buffer-Overflow-Privilege-Escalation.html
generic

Packet Storm

http://packetstormsecurity.com/files/161160/Sudo-Heap-Based-Buffer-Overflow.html

Patch Availability(14)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntusudo-ldap (1.9.1-1ubuntu1.1) @ groovy2026-07-27ubuntu
ubuntusudo (1.8.9p5-1ubuntu1.5+esm6) @ trusty2026-07-27ubuntu
redhatredhat-virtualization-host-0:4.4.4-20210201.0.el8_32021-02-03redhat
redhatredhat-virtualization-host-0:4.3.13-20210127.0.el7_92021-02-03redhat
redhatsudo-0:1.8.23-10.el7_9.12021-01-27redhat
redhatsudo-0:1.8.23-3.el7_6.22021-01-27redhat
redhatsudo-0:1.8.19p2-12.el7_4.22021-01-26redhat
redhatsudo-0:1.8.6p7-17.el7_2.32021-01-26redhat
redhatsudo-0:1.8.6p3-29.el6_10.42021-01-26redhat
redhatsudo-0:1.8.23-4.el7_7.32021-01-26redhat
redhatsudo-0:1.8.29-6.el8_3.12021-01-26redhat
redhatsudo-0:1.8.29-5.el8_2.12021-01-26redhat
redhatsudo-0:1.8.25p1-8.el8_1.22021-01-26redhat
redhatsudo-0:1.8.6p7-23.el7_3.32021-01-26redhat

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 54× in last 7d / 346× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 694 total refreshes for this CVE.

  1. 2026-07-27 10:32 UTCVendor advisory
  2. 2026-07-27 10:31 UTCGHSA enrichment
  3. 2026-07-27 06:30 UTCVendor advisory
  4. 2026-07-27 06:30 UTCGHSA enrichment
  5. 2026-07-27 02:29 UTCVendor advisory
  6. 2026-07-27 02:29 UTCGHSA enrichment
  7. 2026-07-26 22:26 UTCVendor advisory
  8. 2026-07-26 22:26 UTCGHSA enrichment
  9. 2026-07-26 18:25 UTCVendor advisory
  10. 2026-07-26 18:25 UTCGHSA enrichment
  11. 2026-07-26 14:23 UTCEG score recompute
  12. 2026-07-26 14:23 UTCVendor advisory
  13. 2026-07-26 14:23 UTCGHSA enrichment
  14. 2026-07-26 10:22 UTCVendor advisory
  15. 2026-07-26 10:22 UTCGHSA enrichment
  16. 2026-07-26 06:20 UTCVendor advisory
  17. 2026-07-26 06:20 UTCGHSA enrichment
  18. 2026-07-26 02:15 UTCEG score recompute
  19. 2026-07-26 02:15 UTCVendor advisory
  20. 2026-07-26 02:15 UTCGHSA enrichment
  21. 2026-07-25 14:15 UTCEPSS rescore
  22. 2026-07-24 14:15 UTCEPSS rescore
  23. 2026-07-23 02:00 UTCEG score recompute
  24. 2026-07-22 22:47 UTCEG score recompute
  25. 2026-07-22 21:09 UTCVendor advisory
Show 75 more
  1. 2026-07-22 21:08 UTCGHSA enrichment
  2. 2026-07-22 19:40 UTCCISA KEV update
  3. 2026-07-22 17:07 UTCVendor advisory
  4. 2026-07-22 17:07 UTCGHSA enrichment
  5. 2026-07-22 13:06 UTCVendor advisory
  6. 2026-07-22 13:06 UTCGHSA enrichment
  7. 2026-07-22 09:04 UTCVendor advisory
  8. 2026-07-22 09:04 UTCGHSA enrichment
  9. 2026-07-22 05:03 UTCVendor advisory
  10. 2026-07-22 05:03 UTCGHSA enrichment
  11. 2026-07-22 01:00 UTCVendor advisory
  12. 2026-07-22 01:00 UTCGHSA enrichment
  13. 2026-07-21 20:58 UTCVendor advisory
  14. 2026-07-21 20:58 UTCGHSA enrichment
  15. 2026-07-21 16:57 UTCVendor advisory
  16. 2026-07-21 16:56 UTCGHSA enrichment
  17. 2026-07-21 14:37 UTCCISA KEV update
  18. 2026-07-21 12:56 UTCVendor advisory
  19. 2026-07-21 12:55 UTCGHSA enrichment
  20. 2026-07-21 08:55 UTCVendor advisory
  21. 2026-07-21 08:55 UTCGHSA enrichment
  22. 2026-07-21 04:55 UTCVendor advisory
  23. 2026-07-21 04:54 UTCGHSA enrichment
  24. 2026-07-21 00:54 UTCVendor advisory
  25. 2026-07-21 00:54 UTCGHSA enrichment
  26. 2026-07-20 20:54 UTCVendor advisory
  27. 2026-07-20 20:53 UTCGHSA enrichment
  28. 2026-07-20 16:52 UTCVendor advisory
  29. 2026-07-20 16:52 UTCGHSA enrichment
  30. 2026-07-20 12:51 UTCVendor advisory
  31. 2026-07-20 12:51 UTCGHSA enrichment
  32. 2026-07-20 08:50 UTCVendor advisory
  33. 2026-07-20 08:50 UTCGHSA enrichment
  34. 2026-07-20 04:49 UTCVendor advisory
  35. 2026-07-20 04:49 UTCGHSA enrichment
  36. 2026-07-20 00:48 UTCVendor advisory
  37. 2026-07-20 00:48 UTCGHSA enrichment
  38. 2026-07-19 20:47 UTCVendor advisory
  39. 2026-07-19 20:47 UTCGHSA enrichment
  40. 2026-07-19 16:46 UTCVendor advisory
  41. 2026-07-19 16:46 UTCGHSA enrichment
  42. 2026-07-19 12:45 UTCVendor advisory
  43. 2026-07-19 12:45 UTCGHSA enrichment
  44. 2026-07-19 08:45 UTCVendor advisory
  45. 2026-07-19 08:45 UTCGHSA enrichment
  46. 2026-07-19 04:44 UTCVendor advisory
  47. 2026-07-19 04:44 UTCGHSA enrichment
  48. 2026-07-19 00:43 UTCVendor advisory
  49. 2026-07-19 00:43 UTCGHSA enrichment
  50. 2026-07-18 20:41 UTCVendor advisory
  51. 2026-07-18 20:41 UTCGHSA enrichment
  52. 2026-07-18 16:41 UTCVendor advisory
  53. 2026-07-18 16:40 UTCGHSA enrichment
  54. 2026-07-18 12:40 UTCVendor advisory
  55. 2026-07-18 12:40 UTCGHSA enrichment
  56. 2026-07-18 08:39 UTCVendor advisory
  57. 2026-07-18 08:39 UTCGHSA enrichment
  58. 2026-07-18 04:39 UTCVendor advisory
  59. 2026-07-18 04:39 UTCGHSA enrichment
  60. 2026-07-18 00:38 UTCVendor advisory
  61. 2026-07-18 00:38 UTCGHSA enrichment
  62. 2026-07-17 20:37 UTCVendor advisory
  63. 2026-07-17 20:37 UTCGHSA enrichment
  64. 2026-07-17 16:36 UTCVendor advisory
  65. 2026-07-17 16:36 UTCGHSA enrichment
  66. 2026-07-17 12:36 UTCVendor advisory
  67. 2026-07-17 12:36 UTCGHSA enrichment
  68. 2026-07-17 08:35 UTCEG score recompute
  69. 2026-07-17 08:35 UTCVendor advisory
  70. 2026-07-17 08:35 UTCGHSA enrichment
  71. 2026-07-17 04:35 UTCVendor advisory
  72. 2026-07-17 04:35 UTCGHSA enrichment
  73. 2026-07-17 00:35 UTCVendor advisory
  74. 2026-07-17 00:35 UTCGHSA enrichment
  75. 2026-07-16 20:34 UTCVendor advisory

Publicly available exploits

(10 references)

Working exploit code is in the public domain (8 GitHub PoCs) (2 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoC0x4ndy/clif
    First seen Nov 28, 2022

    clif is a command-line interface (CLI) application fuzzer, pretty much what wfuzz or ffuf are for web. It was inspired by sudo vulnerability CVE-2021-3156 and the fact that for some reasons, Google's afl-fuzz doesn't allow for unlimited argument or option specification.

    Open source ↗
  • GitHub PoCLiveOverflow/pwnedit
    First seen Apr 29, 2021

    CVE-2021-3156 - Sudo Baron Samedit

    Open source ↗
  • GitHub PoCworawit/CVE-2021-3156
    First seen Mar 15, 2021

    Sudo Baron Samedit Exploit

    Open source ↗
  • GitHub PoCRvn0xsy/CVE-2021-3156-plus
    First seen Feb 9, 2021

    CVE-2021-3156非交互式执行命令

    Open source ↗
  • GitHub PoC0xdevil/CVE-2021-3156
    First seen Feb 8, 2021

    CVE-2021-3156: Sudo heap overflow exploit for Debian 10

    Open source ↗
  • Exploit-DBEDB-49521
    First seen Feb 3, 2021

    Sudo 1.9.5p1 - 'Baron Samedit ' Heap-Based Buffer Overflow Privilege Escalation (1)

    Open source ↗
  • Exploit-DBEDB-49522
    First seen Feb 3, 2021

    Sudo 1.9.5p1 - 'Baron Samedit ' Heap-Based Buffer Overflow Privilege Escalation (2)

    Open source ↗
  • GitHub PoCCptGibbon/CVE-2021-3156
    First seen Feb 3, 2021

    Root shell PoC for CVE-2021-3156

    Open source ↗
  • GitHub PoCblasty/CVE-2021-3156
    First seen Jan 30, 2021
    Open source ↗
  • GitHub PoCstong/CVE-2021-3156
    First seen Jan 30, 2021

    PoC for CVE-2021-3156 (sudo heap overflow)

    Open source ↗

Frequently asked(6)

What is CVE-2021-3156?
CVE-2021-3156 is a critical 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

Explore the affected products and dependency analysis for CVE-2021-3156

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