CVE-2024-47659
CriticalCVSS 9.1Exploitation Probability (EPSS)
Elevated risk54th percentile - higher than 54% of all known CVEs
Summary
In the Linux kernel, a vulnerability in the Smack module causes incorrect labeling of TCP/IPv4 return packets for incoming connections. The sender's label was mirrored instead of the receiver's label, leading to unauthorized write access.
Risk Assessment
The organization faces risks of data integrity and access control breaches, as a process with label 'bar' can write to a process with label 'foo' without proper authorization, potentially enabling unauthorized data transfer or privilege escalation in Smack-enabled environments.
Recommendation
Apply the official Linux kernel patch that fixes the labeling of return packets in the Smack module immediately, and test systems for compliance with security policies after the update.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: smack: tcp: ipv4, fix incorrect labeling Currently, Smack mirrors the label of incoming tcp/ipv4 connections: when a label 'foo' connects to a label 'bar' with tcp/ipv4, 'foo' always gets 'foo' in returned ipv4 packets. So, 1) returned packets are incorrectly labeled ('foo' instead of 'bar') 2) 'bar' can write to 'foo' without being authorized to write. Here is a scenario how to see this: * Take two machines, let's call them C and S, with active Smack in the default state (no settings, no rules, no labeled hosts, only builtin labels) * At S, add Smack rule 'foo bar w' (labels 'foo' and 'bar' are instantiated at S at this moment) * At S, at label 'bar', launch a program that listens for incoming tcp/ipv4 connections * From C, at label 'foo', connect to the listener at S. (label 'foo' is instantiated at C at this moment) Connection succeedes and works. * Send some data in both directions. * Collect network traffic of this connection. All packets in both directions are labeled with the CIPSO of the label 'foo'. Hence, label 'bar' writes to 'foo' without being authorized, and even without ever being known at C. If anybody cares: exactly the same happens with DCCP. This behavior 1st manifested in release 2.6.29.4 (see Fixes below) and it looks unintentional. At least, no explanation was provided. I changed returned packes label into the 'bar', to bring it into line with the Smack documentation claims.