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How the mentioned CVE works
The vulnerability exists in the IP Virtual Server (IPVS) subsystem of the Linux kernel, which handles load balancing. A previous commit (4754957f04f5) changed the logic so that the source address (saddr) argument for tunnel connections should be ignored. However, the `do_output_route4` function in `ip_vs_xmit.c` incorrectly continued to read from this `saddr` parameter. This parameter could contain an uninitialized value from kernel memory. When the kernel uses this uninitialized data to make routing decisions, it can cause a failure to establish a network route. This flaw is detected by the Kernel Memory Sanitizer (KMSAN) as an “uninit-value” bug. The fix involves changing the function argument to use the `ret_saddr` variable instead, which holds the correct return source address.
Platform:
Linux Kernel
Version:
v2.6.12 onward
Vulnerability:
Uninitialized Memory Read
Severity:
Medium (5.5)
date:
2025-05-20
Prediction:
2025-07-08
What Undercode Say:
Check current kernel version uname -r Verify if IPVS module is loaded lsmod | grep ip_vs Search kernel log for KMSAN warnings dmesg | grep -i "uninit-value" Check for available kernel updates (SUSE) zypper list-updates | grep kernel Check for available kernel updates (Amazon Linux) sudo yum check-update kernel
How Exploit:
Required Access: Local system access.
Complexity: Low complexity attack.
Mechanism: Triggering IPVS tunnel routing.
Privilege: Requires low privileges.
Result: Causes denial-of-service.
Limit: Does not allow code execution.
Protection from this CVE
Apply kernel update.
Patch commit `7d0032112a03`.
Disable IPVS module.
Monitor KMSAN reports.
Use vendor patches.
Impact
Availability: High impact.
Service: Routing failure.
Scope: Unchanged security scope.
Confidentiality: No impact.
Integrity: No impact.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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