CVE-2026-9499Network attack vector

Application crash via unterminated codec-name buffer

Published Jul 21, 2026 · Updated Jul 21, 2026

Qt Framework 4.0.0 through 6.8.7 and 6.9.0 through 6.11.0 has an out-of-bounds read that lets attackers crash applications via codec input. QTextCodec::codecForName() compares a non-NUL-terminated QByteArray against fixed codec names without respecting the array length, so matching reads beyond the supplied buffer. Exposure requires an application to pass such an array; the bounded over-read can select the wrong codec or crash the process but does not disclose data.

CVSS severity6.3
Medium
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Qt Framework 4.0.0 through 6.8.7 and 6.9.0 through 6.11.0 has an out-of-bounds read that lets attackers crash applications via codec input. QTextCodec::codecForName() compares a non-NUL-terminated QByteArray against fixed codec names without respecting the array length, so matching reads beyond the supplied buffer. Exposure requires an application to pass such an array; the bounded over-read can select the wrong codec or crash the process but does not disclose data.

The record

CVE
CVE-2026-9499
Published
Jul 21, 2026
Updated
Jul 21, 2026
Vendor
The Qt Company
Product
Qt Framework
Classifications
CWE-125, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 21, 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=4.0.0 <6.0.0
  2. Affected versionversion=6.0.0 <6.8.8
  3. Affected versionversion=6.9.0 <6.11.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Qt Company · Qt Frameworkversion=4.0.0 <6.0.0; version=6.0.0 <6.8.8; version=6.9.0 <6.11.1

Published CVSS scores

6.3TQtCCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

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 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

CWE-125Out-of-bounds Read
T1499.004Application or System Exploitation

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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