Page generated: 09 Nov 2026, 02:52 UTC
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CVE-2021-3156

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 7.8 (HIGH) KEV: KNOWN CATALOG

Attention and evidence

HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
8.7/10
General review priority; not probability

Evidence confidence: Exploitation recorded

Why this priority?
  • Recorded exploitation baseline: +7.00
  • Technical severity: CVSS 7.8: +1.17
  • Fresh EPSS: 99.96%: +0.50

General review priority, not probability, victim count or asset-specific risk. A range covers missing CVSS/EPSS inputs within the current evidence state.

Sources: 12 documents and public datasets.

Hype components

Headline sample (25%)
0/100
Press, 30 days (60%)
0/100
Grounded branding (15%)
0/100
HYPE TOTAL0/100

Sources and documents

Recorded Future
Press · 08 Sep 2026, 07:00 · August 2026 CVE Landscape - Recorded Future
Huntress
Press · 21 Nov 2025, 08:00 · CVE-2021-3156 Vulnerability: Analysis, Impact, Mitigation - Huntress
The Hacker News
Press · 22 Jun 2024, 07:00 · ExCobalt Cyber Gang Targets Russian Sectors with New GoRed Backdoor - The Hacker News
wiz.io
Press · 22 Mar 2021, 17:06 · Recent Linux sudo vulnerability affects a major percent of cloud workloads - wiz.io
The Hacker News
Press · 10 Feb 2021, 08:00 · Apple Patches 10-Year-Old macOS SUDO Root Privilege Escalation Bug - The Hacker News
See all 12 source documents
MacRumors
Press · 09 Feb 2021, 08:00 · macOS Big Sur 11.2.1 Fixes Root Access Sudo Bug - MacRumors
CrowdStrike.com
Press · 08 Feb 2021, 08:00 · How Falcon Spotlight Helps Detect CVE-2021-3156 Vulnerabilities - CrowdStrike.com
Rapid7
Press · 05 Feb 2021, 08:00 · Metasploit Wrap-Up: Feb. 5, 2021 - Rapid7
MacRumors
Press · 03 Feb 2021, 08:00 · Root Access Sudo Bug Found to Affect macOS Big Sur - MacRumors
SOC Prime
Press · 29 Jan 2021, 08:00 · Heap Buffer Overflow in Sudo (CVE-2021-3156) Enables Privilege Escalation on Linux OS - SOC Prime
Help Net Security
Press · 27 Jan 2021, 08:00 · Sudo vulnerability allows attackers to gain root privileges on Linux systems (CVE-2021-3156) - Help Net Security
BleepingComputer
Press · 26 Jan 2021, 08:00 · New Linux SUDO flaw lets local users gain root privileges - BleepingComputer

Score evolution

● Hype   ● Reality

Earlier evidence-support scores are retained in history; this chart shows only the current priority definition.

First record: hype 0.0 · reality 8.7 (2026-11-02 15:12). The curve appears once the score changes.

Public exploit evidence

7

Public exploit entries / repo candidates

See 7 repos with metrics
RepositoryStarsForksLanguageUpdated
stong/CVE-2021-3156429105C14 Apr 2022, 11:51
CptGibbon/CVE-2021-315615860C13 Feb 2022, 12:21
chenaotian/CVE-2021-3156102C23 May 2022, 01:51
1N53C/CVE-2021-3156-PoC72C06 Feb 2021, 21:20
AbdullahRizwan101/Baron-Samedit10—02 Feb 2021, 12:56
d4ytox/CVE-2021-315610C31 Oct 2026, 16:35
ngtuonghung/CVE-2021-315600Python25 Mar 2026, 14:27
Public exploit evidence
Evidence context and dated references

Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs.

Evidence in context

Confidence in exploitation evidence
Exploitation recorded
Priority basis
Recorded exploitation; CVSS 7.8; EPSS 100.0%
Attention, last 30 days
0 distinct story titles; 0 press documents; 0 publisher domains.
Technical potential
local access, low privileges, no user interaction.
Observed activity
Exploitation recorded in CISA KEV.
Known scale
Not quantified.
Evidence confidence basis
Trusted exploitation confirmation

Score evaluated: 2026-11-05 13:58:26.907878+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline
Published
26 Jan 2021, 00:00
First press mention
26 Jan 2021, 08:00
Added to the CISA KEV catalog
06 Apr 2022, 00:00
Latest press mention
08 Sep 2026, 07:00
Score calculated
05 Nov 2026, 13:58
PoCs on GitHub
7 repositories