CVE-2021-38593Network attack vector

Application crash via zero-extent dashed path

Published Aug 12, 2021 · Updated Aug 4, 2024

Out-of-bounds write in Qt 5.x before 5.15.6 and 6.x through 6.1.2 allows remote attackers to crash applications via crafted paths. QPaintEngineEx::stroke fails to treat a zero-length path extent as pathological, permitting an enormous sequence of tiny dash segments to reach QOutlineMapper::convertPath and write outside its intended buffer. Exploitation requires an affected application to rasterize an attacker-controlled dashed vector path; the bounded demonstrated consequence is an application crash.

CVSS severity7.5
High
EPSS probability3.00%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Qt 5.x before 5.15.6 and 6.x through 6.1.2 allows remote attackers to crash applications via crafted paths. QPaintEngineEx::stroke fails to treat a zero-length path extent as pathological, permitting an enormous sequence of tiny dash segments to reach QOutlineMapper::convertPath and write outside its intended buffer. Exploitation requires an affected application to rasterize an attacker-controlled dashed vector path; the bounded demonstrated consequence is an application crash.

The record

CVE
CVE-2021-38593
Published
Aug 12, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Oracle LinuxCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write

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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