CVE-2025-39758Network attack vector

System crash via oversized sendpage byte count

Published Sep 11, 2025 · Updated Aug 23, 2026

Out-of-bounds access in the Linux kernel RDMA software-iWARP path allows remote attackers to crash systems through crafted network traffic. siw_tcp_sendpages gives a one-page bvec iterator and tcp_sendmsg_locked the full remaining transfer size instead of the current page byte count, so the copy path reads beyond the bvec. Triggering the crash requires software iWARP and a page that cannot use the splice path; the demonstrated consequence is a kernel crash.

CVSS severity9.8
Critical
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds access in the Linux kernel RDMA software-iWARP path allows remote attackers to crash systems through crafted network traffic. siw_tcp_sendpages gives a one-page bvec iterator and tcp_sendmsg_locked the full remaining transfer size instead of the current page byte count, so the copy path reads beyond the bvec. Triggering the crash requires software iWARP and a page that cannot use the splice path; the demonstrated consequence is a kernel crash.

The record

CVE
CVE-2025-39758
Published
Sep 11, 2025
Updated
Aug 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.5
  2. Affected versionversion=a19a58ab12695abb91a4e8ecf62cc0bc5badefbe <b47c4b7cb78b6382c6d1af0bfc0d8218e4f445cc
  3. Affected versionversion=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <42ebc16d9d2563f1a1ce0f05b643ee68d54fabf8
  4. Affected versionversion=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <5661fdd218c2799001b88c17acd19f4395e4488e
  5. Affected versionversion=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <673cf582fd788af12cdacfb62a6a593083542481
  6. Affected versionversion=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <c18646248fed07683d4cee8a8af933fc4fe83c0d
  7. Affected versionversion=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <edf82bc8150570167a33a7d54627d66614cbf841

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.5; version=a19a58ab12695abb91a4e8ecf62cc0bc5badefbe <b47c4b7cb78b6382c6d1af0bfc0d8218e4f445cc; version=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <42ebc16d9d2563f1a1ce0f05b643ee68d54fabf8; version=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <5661fdd218c2799001b88c17acd19f4395e4488e; version=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <673cf582fd788af12cdacfb62a6a593083542481; version=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <c18646248fed07683d4cee8a8af933fc4fe83c0d; version=c2ff29e99a764769eb2ce3a1a5585013633ee9a6 <edf82bc8150570167a33a7d54627d66614cbf841

Published CVSS scores

9.8LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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