Background exploitation KEV catalog
CVE-2021-3156

Sudo Heap-Based Buffer Overflow Vulnerability

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.

CheckOps priority index
7.9/10 Patch within 7 days
Severity7.8
Probability10.0
Exploitation3/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 99.96% higher than 99.98% of CVEs
CVSS 3.1 7.8 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:
Exploited for 1,673 days 06 Apr 2022
CISA due date 27 Apr 2022 for US federal agencies

Exploitation probability EPSS · FIRST

05010026 Sep05 Oct15 Oct24 Oct02 Nov
EPSS probability (%)Percentile among all CVEs

Exploitation signals 3 / 5

  • KEV catalog (CISA)06 Apr 2022
  • Exploited in EUVD (ENISA)06 Apr 2022
  • Used by ransomwareno
  • EPSS above 10 %99.96%
  • No account, over the networkno

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Affected products

Sudo
Weaknesses (CWE)

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

  1. Published

  2. Exploitation reported (ENISA)

  3. Added to the KEV catalog

  4. CISA remediation due date

  5. EPSS peak: 99.96%

References

Other exploited vulnerabilities from the same vendor

  • CVE-2025-32463Sudo Inclusion of Functionality from Untrusted Control Sphere Vulnerability
    7.2 · Background exploitation

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Sources: CISA KEV · ENISA EUVD · FIRST EPSS · OSV. Public data aggregated by CheckOps, updated automatically. Source texts remain the property of their authors. All exploited vulnerabilities