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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-9499

27
FAUCET Score

An out-of-bounds read (buffer over-read) vulnerability exists in QTextCodec::codecForName() in Qt. When the function is called with a QByteArray that is not NUL-terminated (for example, one created with QByteArray::fromRawData()), the codec-name matching routine reads past the end of the supplied buffer. In most cases this results in an incorrect text codec being selected; in the worst case, if the over-read reaches unmapped memory, the process crashes (denial of service). The over-read is bounded by the length of the longest codec-name candidate, and the out-of-bounds bytes are only compared internally against Qt's fixed list of codec names, so no data is disclosed to an attacker. Applications that do not pass non-NUL-terminated QByteArrays to QTextCodec::codecForName() are not exposed. The affected code resides in the Qt5Compat module from Qt 6.0.0 onward, and in Qt Core (qtbase) in Qt 4.x and Qt 5.x.

First published: Jul 21, 2026Last modified: Jul 21, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 6.9.0, < 6.11.1CPE match
cpe:2.3:a:qt:qt:*:*:*:*:*:*:*:*
>= 6.0.0, < 6.8.8CPE match
cpe:2.3:a:qt:qt:*:*:*:*:*:*:*:*
>= 4.0.0, < 6.0.0CPE match
cpe:2.3:a:qt:qt:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

6.3MEDIUM

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
NONE
VS Integrity
LOW
VS Availability
LOW
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.30%
Probability of exploitation in next 30 days
EPSS Percentile
22.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0030 is in the 12th percentile among its peer group of 23,701 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

codereview.qt-project.org / c/qt/qt5compat/+/723911
codereview.qt-project.org / c/qt/qt5compat/+/724348
codereview.qt-project.org / c/qt/qt5compat/+/724995
codereview.qt-project.org / c/qt/tqtc-qt5compat/+/725112