CVE-2026-93228: Linux Vulnerability (CVSS 9.1)

Description

In the Linux kernel, the following vulnerability has been resolved: svcrdma: Reject Write/Reply chunks with segcount 0 A peer can send a Write or Reply chunk whose segcount field is zero. xdr_check_write_chunk() only rejects segcount > rc_maxpages, so zero passes the range check, and xdr_inline_decode(stream, 0) returns the current (non-NULL) cursor without advancing. The function returns true and pcl_alloc_write() then links a struct svc_rdma_chunk with ch_segcount == 0 onto rc_write_pcl or rc_reply_pcl. An earlier patch in this series made pcl_for_each_segment() safe for ch_segcount == 0, so this no longer drives the memory walk it used to. Rejecting the malformed frame at the decode boundary is still worthwhile as defense in depth: it keeps degenerate zero-segment chunks off the parsed chunk lists entirely, so any future consumer that walks ch_segments directly cannot observe one, and it makes the zero-floor easy to backport to trees where the macro change is more intrusive. RFC 8166 has no meaning for a Write/Reply chunk that describes no remote buffer, so no legitimate client is affected. xdr_check_reply_chunk() funnels Reply chunks through xdr_check_write_chunk() and inherits the same rejection. pcl_alloc_write() also links each chunk onto the parsed chunk list before filling its segment array. If a future change weakens the segcount-0 rejection, an incomplete chunk is visible to consumers during the fill loop. Reorder so that list_add_tail() follows the segment fill loop, ensuring only fully-populated chunks appear on the list.

Metrics

CVSS 3.1

9.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2, < fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f; >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2, < a798714b58041e88716db3bf8fb03ae13eecd54a; >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2, < 45dbdb2637b7fc5f1355b588780d2a7fb0516805; >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2, < 9808eb7656666acc7291bae9ab6b987bd16e47e0
Linux	Linux	5.11

References

Timeline

Published: Sep 24, 2026
Last Modified: Sep 25, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-93228?

In the Linux kernel, the following vulnerability has been resolved: svcrdma: Reject Write/Reply chunks with segcount 0 A peer can send a Write or Reply chunk whose segcount field is zero. xdr_check_write_chunk() only rejects segcount > rc_maxpages, so zero passes the range check, and xdr_inline_decode(stream, 0) returns the current (non-NULL) cursor without advancing. The function returns true and pcl_alloc_write() then links a struct svc_rdma_chunk with ch_segcount == 0 onto rc_write_pcl or rc_reply_pcl. An earlier patch in this series made pcl_for_each_segment() safe for ch_segcount == 0, so this no longer drives the memory walk it used to. Rejecting the malformed frame at the decode boundary is still worthwhile as defense in depth: it keeps degenerate zero-segment chunks off the parsed chunk lists entirely, so any future consumer that walks ch_segments directly cannot observe one, and it makes the zero-floor easy to backport to trees where the macro change is more intrusive. RFC 8166 has no meaning for a Write/Reply chunk that describes no remote buffer, so no legitimate client is affected. xdr_check_reply_chunk() funnels Reply chunks through xdr_check_write_chunk() and inherits the same rejection. pcl_alloc_write() also links each chunk onto the parsed chunk list before filling its segment array. If a future change weakens the segcount-0 rejection, an incomplete chunk is visible to consumers during the fill loop. Reorder so that list_add_tail() follows the segment fill loop, ensuring only fully-populated chunks appear on the list.

How severe is CVE-2026-93228?

CVE-2026-93228 has a CVSS score of 9.1/10 (CRITICAL severity).

How do I fix CVE-2026-93228?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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