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CVE-2021-3156 · CVE record: PUBLISHED

Sudo Heap-Based Buffer Overflow Vulnerability

n/a n/a

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.

Exploitation evidence

Known exploited · CISA KEV listed

Added 2022-04-06. Ransomware campaign use: Unknown.

CISA required action: Apply updates per vendor instructions.

CISA due date: 2022-04-27. This is the catalog’s deadline, not an assessment of your organization’s exposure.

KEV checked 13 Nov 2026, 00:20 Jerusalem · Original catalog ↗

Reported products and versions

n/a / n/a

Default status: Not specified

affected: n/a

Fixes and workarounds

No explicit solution text in the downloaded CVE record. Consult the vendor advisory; unaffected version ranges are shown above as reported, not inferred as a patch recommendation.

Sources and related reporting

CVE Program record ↗ · Download tracked evidence as JSON

Observed change timeline

History begins when Egret first downloads each source. It is not the complete upstream CVE history.

12 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-12",
  "epss": 0.99962,
  "percentile": 0.99976
}

10 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-10",
  "epss": 0.99962,
  "percentile": 0.99975
}

09 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-09",
  "epss": 0.99962,
  "percentile": 0.99975
}

08 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-08",
  "epss": 0.99962,
  "percentile": 0.99975
}

07 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-07",
  "epss": 0.99962,
  "percentile": 0.99975
}

06 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-06",
  "epss": 0.99962,
  "percentile": 0.99975
}

06 Nov 2026, 06:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-05",
  "epss": 0.99962,
  "percentile": 0.99975
}

05 Nov 2026, 12:20 Jerusalem · CVE Program record changed

Stored CNA snapshot at this observation.

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04 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-04",
  "epss": 0.99962,
  "percentile": 0.99975
}

03 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-03",
  "epss": 0.99962,
  "percentile": 0.99976
}

03 Nov 2026, 02:22 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-02",
  "epss": 0.99962,
  "percentile": 0.99976
}

03 Nov 2026, 02:22 Jerusalem · CISA KEV status changed

Stored KEV snapshot at this observation.

{
  "cveID": "CVE-2021-3156",
  "cwes": [
    "CWE-122",
    "CWE-193"
  ],
  "dateAdded": "2022-04-06",
  "dueDate": "2022-04-27",
  "forensicTriage": "No",
  "knownRansomwareCampaignUse": "Unknown",
  "notes": "https://nvd.nist.gov/vuln/detail/CVE-2021-3156",
  "product": "Sudo",
  "requiredAction": "Apply updates per vendor instructions.",
  "shortDescription": "Sudo contains an off-by-one error that can result in a heap-based buffer overflow, which allows for privilege escalation.",
  "vendorProject": "Sudo",
  "vulnerabilityName": "Sudo Heap-Based Buffer Overflow Vulnerability"
}

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