CVE-2025-6338Network attack vector

Disk exhaustion via orphaned Schannel RSA files

Published Oct 16, 2025 · Updated Jul 29, 2026

Incomplete cleanup in Qt Schannel support in Qt Framework 5.15.0 through 6.8.3 and 6.9.0 through 6.9.1 allows remote attackers to exhaust disk space. Each accepted TLS connection causes Schannel to create a 4 KB RSA file in the user profile that neither Qt nor the application removes. A Windows server using Schannel is exposed; repeated unauthenticated connections can consume all disk space and interrupt service over time.

CVSS severity9.2
Critical
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incomplete cleanup in Qt Schannel support in Qt Framework 5.15.0 through 6.8.3 and 6.9.0 through 6.9.1 allows remote attackers to exhaust disk space. Each accepted TLS connection causes Schannel to create a 4 KB RSA file in the user profile that neither Qt nor the application removes. A Windows server using Schannel is exposed; repeated unauthenticated connections can consume all disk space and interrupt service over time.

The record

CVE
CVE-2025-6338
Published
Oct 16, 2025
Updated
Jul 29, 2026
Vendor
The Qt Company
Product
Qt Framework
Classifications
CWE-459, T1499.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=5.15.0 <=6.8.3
  2. Affected versionversion=6.9.0 <6.9.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Qt Company · Qt Frameworkversion=5.15.0 <=6.8.3; version=6.9.0 <6.9.2

Published CVSS scores

9.2The Qt CompanyCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-459Incomplete Cleanup
T1499.001OS Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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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