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CVE-1999-1150

19
FAUCET Score

CVE-1999-1150 describes a critical vulnerability in Livingston Portmaster routers running ComOS, where the use of predictable initial sequence numbers (ISNs) for TCP connections allows remote attackers to spoof and hijack active TCP sessions. With a CVSS score of 7.5 (HIGH), this vulnerability is easily exploitable over the network with low complexity, potentially leading to unauthorized access, information disclosure, and denial of service. Despite its age and high severity, there is no evidence of active exploitation, publicly available exploit code in common databases like Metasploit or ExploitDB, or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
initialCPE matchmatch criteria
cpe:2.3:h:livingston_portmaster:portmaster:initial:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

7.5HIGH

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

Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Exploitability Score
10.0
Impact Score
6.4
CvssVersion
2.0

Exploit Intelligence

EPSS Score
1.36%
Probability of exploitation in next 30 days
EPSS Percentile
68.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0136 is in the 49th 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/1882
securityfocus.com / archive/1/9723
Vendor Advisory