CVE-2018-15518: QXmlStream in Qt 5.x before 5.11.3 has a double-free or corruption during parsing of a specially crafted illeg

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HIGH 8.8WATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2018-15518 is a high-severity flaw (CVSS 8.8) affecting qt, debian linux, leap. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

QXmlStream in Qt 5.x before 5.11.3 has a double-free or corruption during parsing of a specially crafted illegal XML document.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Weakness	CWE-415
Published	2018-12-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · opensuse · qt

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-12-26 21:29 UTCPublished CVE record published
2026-06-17 01:42 UTCUpdated Record last modified

qt qt UPGRADE

Affected: >= 5.5.0 and < 5.11.3

Fixed in: 5.11.3

Safe to downgrade to: a release before 5.5.0

1. Check installed version

apt-cache policy qt || rpm -q qt || qt --version

2. UPGRADE to 5.11.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade qt

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade qt

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 5.5.0 (Debian / Ubuntu)

apt-cache madison qt sudo apt install qt=<VERSION_BEFORE_5.5.0> sudo apt-mark hold qt

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list qt sudo dnf downgrade qt-<VERSION_BEFORE_5.5.0> sudo dnf versionlock add qt

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 8.0 · 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

opensuse leap MITIGATE

Affected: 42.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 42.3

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2018-15518?

qt: upgrade to 5.11.3; debian linux: mitigate or apply the listed mitigation; leap: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-15518 being exploited?

CVE-2018-15518 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2018-15518 affect?

CVE-2018-15518 affects qt, debian linux, leap. Severity is high (CVSS 8.8). QXmlStream in Qt 5.x before 5.11.3 has a double-free or corruption during parsing of a specially crafted illegal XML document.

How urgent is CVE-2018-15518?

Priority 57/100. High severity; On your watchlist

Software pages

Debian vulnerabilities

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References

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