CVE-2025-40820CWE-940

CVE-2025-40820

High · published December 9, 2025

CVSS v3.1
7.5
EPSS
0%
Percentile
41.3
In the wild
Unconfirmed
What it is

⚡ A crafty exploit can create chaos with TCP connections! This flaw allows unauthenticated attackers to inject specially crafted packets, potentially disrupting services. 🔥 Think of it like a busy restaurant where the server misreads a few orders and starts mixing up diners’ meals. If timed just right, an attacker can send packets that confuse the network, leading to chaos in communication! An attacker could interfere with connection setups, leading to a denial of service that leaves legitimate users unable to access TCP-based services. Imagine a restaurant where no one gets served because the orders are all wrong—totally frustrating! The impact here could mean downtime and disrupted operations for your services.

Put simply

Think of it like a busy restaurant where the server misreads a few orders and starts mixing up diners’ meals. If timed just right, an attacker can send packets that confuse the network, leading to chaos in communication! This vulnerability arises from the failure to properly validate TCP sequence numbers, which allows attackers to inject IP packets with spoofed addresses during critical moments. This can disrupt the normal flow of connections in TCP-based services.

What to do

An attacker could interfere with connection setups, leading to a denial of service that leaves legitimate users unable to access TCP-based services. Imagine a restaurant where no one gets served because the orders are all wrong—totally frustrating! The impact here could mean downtime and disrupted operations for your services. To mitigate this risk, ensure you implement robust sequence number validation and monitor your network for unusual traffic patterns. Consider applying updates or patches from your vendor as they become available, and review your firewall settings to filter suspicious packets. You’ve got this! By taking these steps, you can fortify your defenses and keep those pesky attackers at bay! 🛡️

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00490 · 41.3th percentile
Weakness
CWE-940 · Improper Verification of Source of a Communication Channel
Published
2025-12-09T21:17Z
References (1)
EPSS history
Timeline
  • 09 DEC 10:44Z
    Affected products do not properly enforce TCP sequence number validation in specific scenarios but accept values within a broad range
    cvelistv5