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NVD / CVE Program· CNA TQtC

CVE-2026-9499: Out-of-bounds read in QTextCodec::codecForName() in Qt

Noroxi assessment

Priority: Monitor (action score 25/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.30% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Qt Qt 6.0.0, 6.11.1, 6.8.8.

Low priority for now. Upgrade to Qt Qt 6.0.0, 6.11.1, 6.8.8 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 6.3 · v4.0—No exploit Fix available
Published
Jul 21, 2026
Updated
Jul 23, 2026
EPSS
0.3% · 22th percentile

Report tools

JSON

Action score

25

Monitor

Low priority for now.

CVSS
25 / 40 · 6.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · TQtC
6.3
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-9499

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (TQtC). Independent of NVD's CPE analysis and usually ahead of it.

  • Qt Qt

    • 6.0.0 and later · before 6.8.8affected · python
    • 6.9.0 and later · before 6.11.1affected · python
    • 4.0.0 and later · before 6.0.0affected · python

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10qt6-qt5compatbefore 6.10.1-1.el10_2.16.10.1-1.el10_2.1
AlmaLinux:10qt6-qt5compat-develbefore 6.10.1-1.el10_2.16.10.1-1.el10_2.1
AlmaLinux:10qt6-qt5compat-examplesbefore 6.10.1-1.el10_2.16.10.1-1.el10_2.1
AlmaLinux:8qt5-qtbasebefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:8qt5-qtbase-commonbefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:8qt5-qtbase-develbefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:8qt5-qtbase-examplesbefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:8qt5-qtbase-guibefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:8qt5-qtbase-mysqlbefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:8qt5-qtbase-odbcbefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:8qt5-qtbase-postgresqlbefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:8qt5-qtbase-private-develbefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:8qt5-qtbase-staticbefore 5.15.3-9.el8_105.15.3-9.el8_10
AlmaLinux:9qt5-qtbasebefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
AlmaLinux:9qt5-qtbase-commonbefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
AlmaLinux:9qt5-qtbase-develbefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
AlmaLinux:9qt5-qtbase-examplesbefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
AlmaLinux:9qt5-qtbase-guibefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
AlmaLinux:9qt5-qtbase-mysqlbefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
AlmaLinux:9qt5-qtbase-odbcbefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
AlmaLinux:9qt5-qtbase-postgresqlbefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
AlmaLinux:9qt5-qtbase-private-develbefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
AlmaLinux:9qt5-qtbase-staticbefore 5.15.9-11.el9_8.15.15.9-11.el9_8.1
Debian:12qt6-5compatfrom 0—

+96

Same product

qt: all records

Other highest-scoring records for the same primary product.

  • CVE-2020-12267setMarkdown in Qt before 5.14.2 has a use-after-free related to QTextMarkdownImporter::insertBlock.
    40Plan
  • CVE-2018-19873An issue was discovered in Qt before 5.11.3.
    40Plan
  • CVE-2017-10904Qt for Android prior to 5.9.0 allows remote attackers to execute arbitrary OS commands via unspecified vectors.
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-6210May 6, 2026 · Type confusion and heap-buffer-overflow in Qt SVG marker handling causing application crash
    34Monitor
  • ← EarlierCVE-2025-14575May 19, 2026 · Uncontrolled Search Path Element in Qt Network OpenSSL TLS backend allows rogue CA certificate loading
    7Monitor
  • Later →CVE-2026-15037Jul 23, 2026 · XML injection vulnerability in QDom comment, CDATA and processing-instruction serialization
    11Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Qt Qt6.0.0Vendor (CNA)
Qt Qt6.11.1Vendor (CNA)
Qt Qt6.8.8Vendor (CNA)
almalinux:qt5-qtbase5.15.3-9.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:qt5-qtbase-common5.15.3-9.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:qt5-qtbase-devel5.15.3-9.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:qt5-qtbase-examples5.15.3-9.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:qt5-qtbase-gui5.15.3-9.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:qt5-qtbase-mysql5.15.3-9.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:qt5-qtbase-odbc5.15.3-9.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:qt5-qtbase-postgresql5.15.3-9.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:qt5-qtbase-private-devel5.15.3-9.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:qt6-qt5compat6.10.1-1.el10_2.1 · AlmaLinux:10Package registry (OSV)
almalinux:qt6-qt5compat-devel6.10.1-1.el10_2.1 · AlmaLinux:10Package registry (OSV)
almalinux:qt6-qt5compat-examples6.10.1-1.el10_2.1 · AlmaLinux:10Package registry (OSV)
debian:qt6-5compat6.10.2-4 · Debian:14Package registry (OSV)
debian:qtbase-opensource-src5.15.19+dfsg-4 · Debian:14Package registry (OSV)
red hat:qt5-qtbase0:5.15.3-9.el8_10 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:qt5-qtbase-common0:5.15.3-9.el8_10 · Red Hat:enterprise_linux:8::appstreamPackage registry (OSV)
red hat:qt60:6.11.1-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-filesystem0:6.11.1-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qt5compat0:6.10.1-1.el10_2.1 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:qt6-qt5compat-debuginfo0:6.10.1-1.el10_2.1 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:qt6-qt5compat-debugsource0:6.10.1-1.el10_2.1 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:qt6-qt5compat-devel0:6.10.1-1.el10_2.1 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:qt6-qt5compat-examples0:6.10.1-1.el10_2.1 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:qt6-qt5compat-examples-debuginfo0:6.10.1-1.el10_2.1 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:qt6-qt5compat-tests-debuginfo0:6.10.1-1.el10_2.1 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:qt6-rpm-macros0:6.11.1-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-srpm-macros0:6.11.1-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)

+2

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-1332652 days apartOut-of-bounds read and integer underflow vulnerability in QNdefNfcTextRecord impacts Qt NFC module
    27Monitor
  • CVE-2026-7615157 days apartOut-of-bounds read (buffer over-read) vulnerability in HTTP Cache-Control response header parsing impacts Qt Framework (QtNetwork module)
    18Monitor
  • CVE-2026-10120191 days apartQBinaryJson::fromBinaryData() integer overflow leading to OOB read
    17Monitor
  • CVE-2025-23050263 days apartQLowEnergyController in Qt before 6.8.2 mishandles malformed Bluetooth ATT commands, leading to an out-of-bounds read (or division by zero).
    12Monitor
  • CVE-2026-10715797 days apartOut-of-bounds read vulnerability in QCborValue::fromCbor() impacts Qt Framework
    8Monitor
  • CVE-2026-7961664 days apartOut-of-bounds read vulnerability in Context2D.path and PathSvg.path properties impacts Qt Quick
    2Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records