CVE-2025-38501Public exploitNetwork attack vector

Unauthenticated SMB service interruption via idle connections

Published Aug 16, 2025 · Updated Aug 5, 2026

Resource exhaustion in Linux ksmbd from 5.15 allows remote attackers to interrupt SMB service via idle TCP connections. The TCP accept path allocates a connection slot and kernel thread before SMB negotiation, then retains silent connections indefinitely because per-IP admission control is absent and deadtime defaults to zero. A completed TCP handshake requires no credentials; repeated idle connections from one address can deny SMB access to other clients and, without a global limit, exhaust kernel threads, memory, and CPU.

CVSS severity7.5
High
EPSS probability2.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Linux ksmbd from 5.15 allows remote attackers to interrupt SMB service via idle TCP connections. The TCP accept path allocates a connection slot and kernel thread before SMB negotiation, then retains silent connections indefinitely because per-IP admission control is absent and deadtime defaults to zero. A completed TCP handshake requires no credentials; repeated idle connections from one address can deny SMB access to other clients and, without a global limit, exhaust kernel threads, memory, and CPU.

The record

CVE
CVE-2025-38501
Published
Aug 16, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=0626e6641f6b467447c81dd7678a69c66f7746cf <6073afe64510c302b7a0683a01e32c012eff715d
  2. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <7e5d91d3e6c62a9755b36f29c35288f06c3cd86b
  3. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <cb092fc3a62972a4aa47c9fe356c2c6a01cd840b
  4. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <e6bb9193974059ddbb0ce7763fa3882bd60d4dc3
  5. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <f1ce9258bcbce2491f9f71f7882b6eed0b33ec65
  6. Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <fa1c47af4ff641cf9197ecdb1f8240cbb30389c1
  7. Affected versionversion=5.15

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0626e6641f6b467447c81dd7678a69c66f7746cf <6073afe64510c302b7a0683a01e32c012eff715d; version=0626e6641f6b467447c81dd7678a69c66f7746cf <7e5d91d3e6c62a9755b36f29c35288f06c3cd86b; version=0626e6641f6b467447c81dd7678a69c66f7746cf <cb092fc3a62972a4aa47c9fe356c2c6a01cd840b; version=0626e6641f6b467447c81dd7678a69c66f7746cf <e6bb9193974059ddbb0ce7763fa3882bd60d4dc3; version=0626e6641f6b467447c81dd7678a69c66f7746cf <f1ce9258bcbce2491f9f71f7882b6eed0b33ec65; version=0626e6641f6b467447c81dd7678a69c66f7746cf <fa1c47af4ff641cf9197ecdb1f8240cbb30389c1; version=5.15

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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