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CVE-1999-0556

25
FAUCET Score

CVE-1999-0556 identifies a critical security misconfiguration within Unix environments where two or more accounts are assigned the same User Identifier (UID), potentially blurring privilege boundaries. This vulnerability carries a maximum CVSS score of 10.0 due to its potential for remote exploitation with low complexity, allowing unauthorized actors to fully compromise system confidentiality, integrity, and availability. Despite its high theoretical risk and a FAUCET Risk Score of 81, there is currently no evidence of active exploitation, public exploit code, or recent community discussion surrounding this legacy issue.

Impacted Technologies

VendorProductVersion(s)CPE
N/AN/A
n/aCNA affected

CVSS Data

CVSS version used by this source: 2.0

10.0HIGH

AV:N/AC:L/Au:N/C:C/I:C/A:C

Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
10.0
CvssVersion
2.0

Exploit Intelligence

EPSS Score
1.89%
Probability of exploitation in next 30 days
EPSS Percentile
77.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0189 is in the 61st percentile among its peer group of 51,551 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

exchange.xforce.ibmcloud.com / vulnerabilities/876