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NVD / CVE Program· CNA Qt

CVE-2026-78253: Denial-of-service (stack-exhaustion) vulnerability in QXmlStreamReader::readElementText() impacts Qt

Noroxi assessment

Priority: Monitor (action score 9/100)

  • 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: 0.42% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No special conditions are required; it is repeatable.
  • Fixed version: azl3 qtbase 6.6.3-6 on Azure Linux 3.0 6.6.3-7; azl3 qtbase 6.6.3-7 on Azure Linux 3.0 6.6.3-7.

Low priority for now. Upgrade to azl3 qtbase 6.6.3-6 on Azure Linux 3.0 6.6.3-7; azl3 qtbase 6.6.3-7 on Azure Linux 3.0 6.6.3-7 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

Uncontrolled recursion in QXmlStreamReader::readElementText() in Qt Group Qt allows attackers to cause a denial of service (application crash via stack exhaustion) via a crafted XML document.

LowCVSS 2.3 · v4.0—No exploit Fix available
Published
Sep 23, 2026
Updated
Sep 24, 2026
EPSS
0.4% · 37th percentile

Report tools

JSON

Action score

9

Monitor

Low priority for now.

CVSS
9 / 40 · 2.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Qt
2.3
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:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/S:N/AU:N/R:U/RE:L/U:Green

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-2026-78253

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 (Qt). Independent of NVD's CPE analysis and usually ahead of it.

  • qt qt

    • 5.0.0 and later · up to and including 6.8.8affected · python
    • 6.9.0 and later · up to and including 6.11.1affected · python

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12qt6-basefrom 0—
Debian:12qtbase-opensource-srcfrom 0—
Debian:14qt6-basebefore 6.11.2+dfsg-56.11.2+dfsg-5
Debian:14qtbase-opensource-srcbefore 5.15.19+dfsg-65.15.19+dfsg-6
openSUSE:TumbleweedAusweisAppbefore 2.6.0-1.12.6.0-1.1
Red Hat:hummingbird:1qt6-qtbasebefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-commonbefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-develbefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-examplesbefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-guibefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-ibasebefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-mysqlbefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-odbcbefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-postgresqlbefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-private-develbefore 0:6.11.2-2.hum10:6.11.2-2.hum1
Red Hat:hummingbird:1qt6-qtbase-staticbefore 0:6.11.2-2.hum10:6.11.2-2.hum1

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-2026-76151Sep 16, 2026 · Out-of-bounds read (buffer over-read) vulnerability in HTTP Cache-Control response header parsing impacts Qt Framework (QtNetwork module)
    18Monitor
  • ← EarlierCVE-2026-79616Sep 23, 2026 · Out-of-bounds read vulnerability in Context2D.path and PathSvg.path properties impacts Qt Quick
    2Monitor
  • Later →CVE-2026-79680Sep 24, 2026 · Authentication bypass vulnerability in the password authentication mechanism of the Qt VNC Server module
    18Monitor

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
azl3 qtbase 6.6.3-6 on Azure Linux 3.06.6.3-7 · Release NotesMicrosoft (MSRC)
azl3 qtbase 6.6.3-7 on Azure Linux 3.06.6.3-7 · Release NotesMicrosoft (MSRC)
debian:qt6-base6.11.2+dfsg-5 · Debian:14Package registry (OSV)
debian:qtbase-opensource-src5.15.19+dfsg-6 · Debian:14Package registry (OSV)
opensuse:AusweisApp2.6.0-1.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:qt6-qtbase0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-common0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-devel0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-examples0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-gui0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-ibase0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-mysql0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-odbc0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-postgresql0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-private-devel0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:qt6-qtbase-static0:6.11.2-2.hum1 · Red Hat:hummingbird:1Package registry (OSV)

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-2025-10728355 days apartUncontrolled recursion in Qt SVG module
    37Monitor
  • CVE-2026-192487 days apartUnbounded recursion vulnerability in the QDomNode destructor of Qt XML impacts Qt
    28Monitor
  • CVE-2026-1157315 days apartUncontrolled recursion in QDomDocument/QDomNode serialization causes stack exhaustion (QtXml)
    28Monitor
  • CVE-2026-816826 days apartDenial-of-service vulnerability in the SVG parser and renderer impacts Qt
    28Monitor

Chain candidates

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

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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 special conditions are required; it is repeatable.

If successful

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

Weakness class (CWE)

CWE-674 · Uncontrolled Recursion

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/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:N/AU:N/R:U/V:X/RE:L/U:Green

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

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

All records