CVE-2026-68425
Received Received - Intake

IB/mad RMPP Response Handling Flaw in Linux Kernel

Vulnerability report for CVE-2026-68425, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: IB/mad: Drop unmatched RMPP responses before reassembly Kernel-handled RMPP receive processing starts reassembly for active DATA responses before the response is matched to an outstanding send. The normal match happens later, after ib_process_rmpp_recv_wc() has either assembled a complete message or consumed the segment. That ordering lets an unsolicited response that routes to a kernel RMPP agent by the high TID bits allocate or extend RMPP receive state before the full TID and source address are checked against a real request. A reordered burst can therefore reach the receive-side insertion path even though the response would not match any send. For kernel-handled RMPP DATA responses, require the existing ib_find_send_mad() match before entering RMPP reassembly. The matcher already checks the full TID, management class and source address/GID against the agent wait, backlog and in-flight send lists. If there is no match, drop the response without creating RMPP state. This leaves the RMPP window behavior unchanged and only rejects responses that have no corresponding request.

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Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves improper handling of RMPP (Reliable Datagram Congestion Control Protocol Message Passing) responses. The kernel starts reassembling DATA responses before verifying if they match an outstanding request. This allows unsolicited responses to allocate or extend RMPP receive state incorrectly, potentially leading to mismatched or corrupted data processing.

Detection Guidance

This vulnerability affects the Linux kernel's IB/mad RMPP reassembly process. Detection requires checking kernel logs for RMPP-related errors or monitoring network traffic for unsolicited RMPP responses. Use commands like 'dmesg | grep RMPP' or 'journalctl -k | grep RMPP' to inspect kernel logs for reassembly failures or unexpected responses.

Impact Analysis

This vulnerability could allow unauthorized or malformed data to be processed by the kernel, potentially causing system instability, crashes, or unexpected behavior. It may also enable denial-of-service conditions by consuming kernel resources improperly.

Mitigation Strategies

Apply the latest kernel update from your Linux distribution to patch the IB/mad RMPP reassembly flaw. If immediate patching is not possible, consider disabling RMPP-related services or isolating affected systems until the update is applied.

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