CVE-2026-9499: CWE-125 Out-of-bounds Read in Qt
CVE-2026-9499 is a medium severity out-of-bounds read vulnerability in the Qt framework affecting QTextCodec::codecForName(). It occurs when the function is called with a non-NUL-terminated QByteArray, causing the codec-name matching routine to read past the buffer end. This can lead to incorrect codec selection or, in rare cases, process crashes due to reading unmapped memory. The vulnerability affects Qt versions prior to 6.0.0, exactly 6.0.0, and exactly 6.9.0. No data disclosure occurs, and applications not passing non-NUL-terminated QByteArrays to this function are not vulnerable.
AI Analysis
Technical Summary
An out-of-bounds read vulnerability exists in QTextCodec::codecForName() in Qt. When called with a QByteArray that is not NUL-terminated (e.g., created with QByteArray::fromRawData()), the codec-name matching routine reads beyond the buffer boundary. This over-read is limited by the length of the longest codec-name candidate and only compares bytes internally against Qt's fixed codec name list. The vulnerability can cause incorrect codec selection or, if the over-read accesses unmapped memory, a process crash (denial of service). The affected code is in the Qt5Compat module from Qt 6.0.0 onward and in Qt Core (qtbase) in Qt 4.x and Qt 5.x. Applications that do not pass non-NUL-terminated QByteArrays to this function are not exposed.
Potential Impact
The vulnerability can cause incorrect text codec selection, potentially affecting application behavior. In the worst case, it can cause a denial of service by crashing the process if the over-read accesses unmapped memory. There is no data disclosure or code execution impact. Only applications passing non-NUL-terminated QByteArrays to QTextCodec::codecForName() are affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid passing non-NUL-terminated QByteArrays to QTextCodec::codecForName() to prevent triggering the vulnerability.
CVE-2026-9499: CWE-125 Out-of-bounds Read in Qt
Description
CVE-2026-9499 is a medium severity out-of-bounds read vulnerability in the Qt framework affecting QTextCodec::codecForName(). It occurs when the function is called with a non-NUL-terminated QByteArray, causing the codec-name matching routine to read past the buffer end. This can lead to incorrect codec selection or, in rare cases, process crashes due to reading unmapped memory. The vulnerability affects Qt versions prior to 6.0.0, exactly 6.0.0, and exactly 6.9.0. No data disclosure occurs, and applications not passing non-NUL-terminated QByteArrays to this function are not vulnerable.
CVSS v4.0
Score 6.3medium
Affected software
cpe:2.3:a:qt:qt:*:*:*:*:*:*:*:*Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
An out-of-bounds read vulnerability exists in QTextCodec::codecForName() in Qt. When called with a QByteArray that is not NUL-terminated (e.g., created with QByteArray::fromRawData()), the codec-name matching routine reads beyond the buffer boundary. This over-read is limited by the length of the longest codec-name candidate and only compares bytes internally against Qt's fixed codec name list. The vulnerability can cause incorrect codec selection or, if the over-read accesses unmapped memory, a process crash (denial of service). The affected code is in the Qt5Compat module from Qt 6.0.0 onward and in Qt Core (qtbase) in Qt 4.x and Qt 5.x. Applications that do not pass non-NUL-terminated QByteArrays to this function are not exposed.
Potential Impact
The vulnerability can cause incorrect text codec selection, potentially affecting application behavior. In the worst case, it can cause a denial of service by crashing the process if the over-read accesses unmapped memory. There is no data disclosure or code execution impact. Only applications passing non-NUL-terminated QByteArrays to QTextCodec::codecForName() are affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid passing non-NUL-terminated QByteArrays to QTextCodec::codecForName() to prevent triggering the vulnerability.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- TQtC
- Date Reserved
- 2026-05-25T09:55:56.600Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a5f7ac92a4a8d598939c056
Added to database: 07/21/2026, 13:57:29 UTC
Last enriched: 07/21/2026, 14:11:45 UTC
Last updated: 07/21/2026, 14:54:03 UTC
Views: 5
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