CVE-2026-93228
📛 CVE Title
svcrdma: Reject Write/Reply chunks with segcount 0
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.
Overview
- State
- PUBLISHED
- Assigner (CNA)
- Linux
- CVSS severity
- CRITICAL
- CVSS score
- 9.1 / 10
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H- Effective score
- 9.1 / 10 CRITICAL source: CNA overview
- CWE(s)
- —
- Reserved
- 2026-09-17
- Published
- 2026-09-24 15:29 UTC
- Last updated
- 2026-09-25 05:09 UTC
- Source
- https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/93xxx/CVE-2026-93228.json
- Linked Threat
- CVE-2026-93228 — svcrdma: Reject Write/Reply chunks with segcount 0
NVD / KEV / EPSS data refreshed 2026-09-25 04:32 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.
European Union Vulnerability Database ENISA EUVD
ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.
- EUVD ID
-
EUVD-2026-86233 - Assigner
- Linux
- Published
- Sep 24, 2026, 3:29:10 PM
- Updated
- Sep 25, 2026, 5:09:48 AM
- EUVD base score (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 - EUVD-reported EPSS
- 0.0000
- Vendors
- Linux
- Products
-
Linux (5.11)Linux (78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 <9808eb7656666acc7291bae9ab6b987bd16e47e0)Linux (patch: 0)Linux (78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 <a798714b58041e88716db3bf8fb03ae13eecd54a)Linux (78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 <45dbdb2637b7fc5f1355b588780d2a7fb0516805)Linux (78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 <fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f)Linux (patch: 6.12.111)Linux (patch: 7.2.4)Linux (patch: 7.3-rc1)Linux (patch: 6.18.50)
- Aliases
-
GHSA-g29j-c673-5ccw
ENISA 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.
EUVD references (4)
Affected products (2)
| Vendor | Product | Versions | Platforms |
|---|---|---|---|
| Linux | Linux |
78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 (affected),
78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 (affected),
78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 (affected),
78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 (affected)
|
— |
| Linux | Linux |
5.11 (affected),
0 (unaffected),
6.12.111 (unaffected),
6.18.50 (unaffected),
7.2.4 (unaffected),
7.3-rc1 (unaffected)
|
— |
Vendor references (4)
References embedded in the original CVE record by the assigning CNA.
Web references (0)
DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.
No web references attached yet.
Remediations (12)
Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.
-
web:byteiota.com
That's not all. September's Patch Tuesday also fixed two zero-days under active exploitation: CVE - 2026 -85880, a heap buffer overflow in Windows ALPC that allows local privilege escalation to SYSTEM, and CVE - 2026 -81963, a link-following flaw in the Windows Update Stack. Rolling back removes those fixes too.
2026-09-25 10:45 UTC -
web:msrc.microsoft.com
The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.
2026-09-25 10:45 UTC -
web:sec.cloudapps.cisco.com
On September 16, 2026 , the Cisco Product Security Incident Response Team (PSIRT) published the advisories that are listed in the following tables. To remediate these vulnerabilities, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories. For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the ...
2026-09-25 10:45 UTC -
web:securityaffairs.com
A Veeam Agent flaw lets local users gain SYSTEM privileges. A public PoC is available, raising the risk of exploitation on shared Windows systems. If you're running Veeam Agent on a Windows endpoint with more than one local user, now's the time to check the version, not tomorrow. On September 14, 2026 , public technical details and a proof-of-concept exploit dropped for CVE - 2026 -32996. From ...
2026-09-25 10:45 UTC -
web:windowsforum.com
Microsoft published CVE - 2026 -62878 on August 11 as a Windows DNS Server Remote Code Execution Vulnerability, putting systems that run the Windows DNS Server role into the immediate patch -and-verify queue.
2026-09-25 10:45 UTC -
web:www.action1.com
This CISO-focused summary highlights the vulnerabilities and critical infrastructure risks that should take priority for remediation following Microsoft's September 2026 Patch Tuesday release.
2026-09-25 10:45 UTC -
web:www.cisecurity.org
<p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...
2026-09-25 10:45 UTC -
web:www.oracle.com
This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.
2026-09-25 10:45 UTC -
web:www.oracle.com
This Critical Patch Update contains 1448 new security patches across the product families listed below. Please note that a My Oracle Support (MOS) note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at July 2026 Critical Patch Update: Executive Summary and Analysis.
2026-09-25 10:45 UTC -
web:www.secpod.com
Patch Timeline & Exploitation Gap Analysis The September 16, 2026 dataset contains three CISA KEV vulnerabilities. Each record was added to the catalog on September 16, 2026 and assigned a remediation deadline of September 19, 2026 . Consequently, all three vulnerabilities have an identical three-calendar-day KEV inclusion-to- remediation window.
2026-09-25 10:45 UTC -
web:support.microsoft.com
Be aware that the update in the Microsoft Download Center applies to the Microsoft Installer (.msi)-based edition of Office 2016. It doesn't apply to the Office 2016 Click-to-Run editions, such as Microsoft Office 365 Home. (See What version of Office am I using?) How to get and install the update Method 1: Microsoft Update This update is available from Microsoft Update. When you turn on ...
2026-09-25 15:07 UTC -
web:www.theregister.com
F5 has fixed a critical zero-day bug in its BIG-IP Access Policy Manager (APM) that unknown miscreants are exploiting to remotely execute malicious code. BIG-IP APM is a centralized access management and security proxy that allows users to connect to enterprise networks, applications, APIs, and cloud services via a single login. The flaw, tracked as CVE - 2026 -94127, is a heap-based buffer ...
2026-09-25 15:07 UTC
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Raw JSON
The full cvelistV5 record. Download as CVE-2026-93228.json.
{
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"defaultStatus": "unaffected",
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"programFiles": [
"net/sunrpc/xprtrdma/svc_rdma_pcl.c",
"net/sunrpc/xprtrdma/svc_rdma_recvfrom.c"
],
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{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
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{
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"status": "unaffected",
"version": "6.18.50",
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{
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{
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"status": "unaffected",
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}
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsvcrdma: Reject Write/Reply chunks with segcount 0\n\nA peer can send a Write or Reply chunk whose segcount field is zero.\nxdr_check_write_chunk() only rejects segcount > rc_maxpages, so zero\npasses the range check, and xdr_inline_decode(stream, 0) returns the\ncurrent (non-NULL) cursor without advancing. The function returns\ntrue and pcl_alloc_write() then links a struct svc_rdma_chunk with\nch_segcount == 0 onto rc_write_pcl or rc_reply_pcl.\n\nAn earlier patch in this series made pcl_for_each_segment() safe for\nch_segcount == 0, so this no longer drives the memory walk it used\nto. Rejecting the malformed frame at the decode boundary is still\nworthwhile as defense in depth: it keeps degenerate zero-segment\nchunks off the parsed chunk lists entirely, so any future consumer\nthat walks ch_segments directly cannot observe one, and it makes the\nzero-floor easy to backport to trees where the macro change is more\nintrusive. RFC 8166 has no meaning for a Write/Reply chunk that\ndescribes no remote buffer, so no legitimate client is affected.\n\nxdr_check_reply_chunk() funnels Reply chunks through\nxdr_check_write_chunk() and inherits the same rejection.\n\npcl_alloc_write() also links each chunk onto the parsed chunk list\nbefore filling its segment array. If a future change weakens the\nsegcount-0 rejection, an incomplete chunk is visible to consumers\nduring the fill loop. Reorder so that list_add_tail() follows the\nsegment fill loop, ensuring only fully-populated chunks appear on\nthe list."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.1,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - A remote NFS/RDMA peer places a Write or Reply chunk with segcount 0 in the RPC-over-RDMA transport header; svc_rdma_recvfrom() \u2192 svc_rdma_xdr_decode_req() \u2192 xdr_check_write_list()/xdr_check_reply_chunk() \u2192 xdr_check_write_chunk() accepted that field over iWARP or routable RoCEv2.\nAC:L - The attacker sets RPCRDMA_CMP_F_SND_W_INV_OK in the RDMA-CM private connect blob (svc_rdma_parse_connect_private) and sends a Write/Reply chunk with segcount 0; xdr_check_write_chunk() only rejected segcount > rc_maxpages, xdr_inline_decode(0) returns the cursor, and pcl_alloc_write() links a ch_segcount==0 chunk with no race.\nPR:N - xdr_check_write_chunk() and pcl_alloc_write() run in svc_rdma_xdr_decode_req() from svc_rdma_recvfrom() while parsing the transport header, before svc_xprt_do_recv() calls svc_process()/svc_authenticate(); RDMA CM accept performs no NFS credential check.\nUI:N - The attacker only needs to connect to a listening NFS/RDMA service and send an RPC-over-RDMA Call whose Write list or Reply chunk has segcount 0; no victim mount, click, or other user action is required.\nS:U - pcl_alloc_write() installs the empty chunk on the host kernel rc_write_pcl/rc_reply_pcl, and the subsequent heap walk and general protection fault stay inside nfsd's RPC-over-RDMA server; this is not a VM, IOMMU, or sandbox escape.\nC:H - Accepting segcount 0 in xdr_check_write_chunk() lets pcl_alloc_write() put a ch_segcount==0 Write/Reply chunk on the parsed list; pcl_for_each_segment then uses &ch_segments[0u-1u] and walks adjacent kernel heap at sizeof(struct svc_rdma_segment) stride, an unbounded out-of-bounds read.\nI:N - svc_rdma_get_inv_rkey() only loads segment->rs_handle from the overrun pointer to choose an invalidate rkey; Write/Reply encode and RDMA Write paths index with segno < ch_segcount and skip or return -E2BIG on an empty chunk, so there is no out-of-bounds write or control-flow hijack.\nA:H - The underflowed pcl_for_each_segment walk of the empty Write/Reply chunk continues until it hits unmapped memory and raises a general protection fault, oopsing or panicking the kernel, and the peer can send another zero-segcount Call to repeat it."
}
]
}
],
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"dateUpdated": "2026-09-25T05:09:48.089Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"references": [
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"url": "https://git.kernel.org/stable/c/fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f"
},
{
"url": "https://git.kernel.org/stable/c/a798714b58041e88716db3bf8fb03ae13eecd54a"
},
{
"url": "https://git.kernel.org/stable/c/45dbdb2637b7fc5f1355b588780d2a7fb0516805"
},
{
"url": "https://git.kernel.org/stable/c/9808eb7656666acc7291bae9ab6b987bd16e47e0"
}
],
"title": "svcrdma: Reject Write/Reply chunks with segcount 0",
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"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-93228",
"datePublished": "2026-09-24T15:29:10.087Z",
"dateReserved": "2026-09-17T16:02:15.094Z",
"dateUpdated": "2026-09-25T05:09:48.089Z",
"state": "PUBLISHED"
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