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CVE-1999-0656

15
FAUCET Score

CVE-1999-0656 describes an information disclosure vulnerability in the ugidd RPC interface, affecting the Linux kernel. This flaw allows remote attackers to enumerate valid usernames by querying arbitrary User IDs (UIDs) that ugidd attempts to map to local user and group names. Rated Medium severity (CVSS 5.0), it has a low attack complexity and requires no authentication, but only impacts confidentiality by revealing usernames. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage for this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
All Versions ImpactedCPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

5.0MEDIUM

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

Confidentiality Impact
PARTIAL
Integrity Impact
NONE
Availability Impact
NONE
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
2.9
CvssVersion
2.0

Exploit Intelligence

EPSS Score
1.55%
Probability of exploitation in next 30 days
EPSS Percentile
72.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0155 is in the 56th percentile among its peer group of 23,705 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, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

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

Remediation

Patch Available

Vendor Patches (10)

microsoftpatch availablevia msrc
Product: cm1 kernel 5.10.60.1-1 on CBL Mariner 1.0Fixed in: -
microsoftpatch availablevia msrc
Product: cbl2 kernel 5.10.78.1-1 on CBL Mariner 2.0Fixed in: 5.10.78.1-1
microsoftpatch availablevia msrc
Product: azl3 kernel 6.6.35.1-4 on Azure Linux 3.0Fixed in: 6.6.35.1-4
microsoftpatch availablevia msrc
Product: azl3 kernel 6.6.92.2-1 on Azure Linux 3.0Fixed in: 6.6.35.1-4
microsoftpatch availablevia msrc
Product: 16919-16820Fixed in: -
microsoftpatch availablevia msrc
Product: 16920-16823Fixed in: 5.10.78.1-1
microsoftpatch availablevia msrc
Product: 17065-17084Fixed in: 6.6.35.1-4
microsoftpatch availablevia msrc
Product: 19529-17084Fixed in: 6.6.35.1-4
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 5.10.60.1-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 5.10.60.1-1

Vendor Advisories (2)

microsoft2020-Sep/CVE-1999-0656

CVE-1999-0656

Sep 8, 2020
microsoft2000-Feb/CVE-1999-0656Moderate

The ugidd RPC interface by design allows remote attackers to enumerate valid usernames by specifying arbitrary UIDs that ugidd maps to local user and group names.

Feb 2, 2000

References

ca.com / au/securityadvisor/vulninfo/Vuln.aspx
exchange.xforce.ibmcloud.com / vulnerabilities/348