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CVE-2021-3899

24
FAUCET Score

CVE-2021-3899 describes a race condition in the 'replaced executable' detection mechanism within Canonical's Apport and Ubuntu Linux, allowing a local attacker to execute arbitrary code as root. With a CVSS score of 7.8 (High), this vulnerability has a low attack complexity and requires local user privileges, but can lead to complete compromise of confidentiality, integrity, and availability. Despite its severity, there is no evidence of active exploitation, no public exploit code (Metasploit, Nuclei, ExploitDB), and minimal community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 2.21.0CPE matchmatch criteria
cpe:2.3:a:canonical:apport:*:*:*:*:*:*:*:*
18.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
20.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*
21.10CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:21.10:*:*:*:*:*:*:*
22.04CPE matchmatch criteria
cpe:2.3:o:canonical:ubuntu_linux:22.04:*:*:*:lts:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.38%
Probability of exploitation in next 30 days
EPSS Percentile
31.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0038 is in the 70th percentile among its peer group of 16,994 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

ubuntuvendor investigatingvia nvd_reference
View patch

References

bugs.launchpad.net / ubuntu/+source/apport/+bug/1948376
Issue TrackingPatch
ubuntu.com / security/notices/USN-5427-1
Vendor Advisory
cve.org / CVERecord
Third Party Advisory