CVE-2023-51714: An issue was discovered in the HTTP2 implementation in Qt before 5.15.17, 6.x before 6.2.11, 6.3.x through 6.5

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CRITICAL 9.8REMOTEWATCHLISTMITIGATEUPGRADE

CVE-2023-51714 is a critical-severity flaw (CVSS 9.8) affecting debian linux, qt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in the HTTP2 implementation in Qt before 5.15.17, 6.x before 6.2.11, 6.3.x through 6.5.x before 6.5.4, and 6.6.x before 6.6.2. network/access/http2/hpacktable.cpp has an incorrect HPack integer overflow check.

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 38%)
CISA exploited list	No
Weakness	CWE-190
Published	2023-12-24
Last modified	2026-10-08

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

Last updated 2026-10-08 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-12-24 21:15 UTCPublished CVE record published
2026-10-08 22:17 UTCUpdated Record last modified

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

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.

qt qt UPGRADE

Affected: >= 5.7 and < 5.15.17 · >= 6.0.0 and < 6.2.11 · >= 6.3.0 and < 6.5.4 · >= 6.6.0 and < 6.6.2

Fixed in: 5.15.17, 6.2.11, 6.5.4, 6.6.2

Safe to downgrade to: a release before 5.7

1. Check installed version

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

2. UPGRADE to 5.15.17 (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 5.7 (Debian / Ubuntu)

apt-cache madison qt sudo apt install qt=<VERSION_BEFORE_5.7> 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_5.7> 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.

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-2023-51714?

debian linux: mitigate or apply the listed mitigation; qt: upgrade to 5.15.17, 6.2.11, 6.5.4, 6.6.2. Exact commands for each OS are on this page.

Is CVE-2023-51714 being exploited?

CVE-2023-51714 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-2023-51714 affect?

CVE-2023-51714 affects debian linux, qt. Severity is critical (CVSS 9.8). An issue was discovered in the HTTP2 implementation in Qt before 5.15.17, 6.x before 6.2.11, 6.3.x through 6.5.x before 6.5.4, and 6.6.x before 6.6.2. network/access/http2/hpacktable.cpp has an incorrect HPack integer overflow check.

How urgent is CVE-2023-51714?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

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References

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