---
id: CVE-1999-0077
title: Predictable TCP sequence numbers allow spoofing.
summary: Predictable TCP sequence numbers allow spoofing.
severity: medium
cvss: 5
cvssVector: 'AV:N/AC:L/Au:N/C:P/I:N/A:N'
published: '1995-01-01'
updated: '2026-06-16'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-1999-0077'
references:
  - url: 'https://exchange.xforce.ibmcloud.com/vulnerabilities/139'
    label: cve@mitre.org
  - url: 'https://exchange.xforce.ibmcloud.com/vulnerabilities/139'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - exploit-available
epss: 0.31392
epssPercentile: 0.982
ingestedAt: '2026-06-19T03:39:00.748Z'
exploitAvailable: true
exploits:
  exploitdb: true
  checkedAt: '2026-09-23T07:13:13.423Z'
---

## Overview

Predictable TCP sequence numbers allow spoofing.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.