CVE-2023-42805: quinn-proto is a state machine for the QUIC transport protocol

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HIGH 7.5REMOTEUPGRADE

CVE-2023-42805 is a high-severity flaw (CVSS 7.5) affecting quinn. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

quinn-proto is a state machine for the QUIC transport protocol. Prior to versions 0.9.5 and 0.10.5, receiving unknown QUIC frames in a QUIC packet could result in a panic. The problem has been fixed in 0.9.5 and 0.10.5 maintenance releases.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 39%)
CISA exploited list	No
Weakness	CWE-20
Published	2023-09-21
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: quinn project

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

Am I affected?

Timeline

2023-09-21 17:15 UTCPublished CVE record published
2026-06-17 06:24 UTCUpdated Record last modified

quinn project quinn UPGRADE

Affected: < 0.9.5 · >= 0.10.0 and < 0.10.5

Fixed in: 0.9.5, 0.10.5

Safe to downgrade to: a release before 0.10.0

1. Check installed version

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

2. UPGRADE to 0.9.5 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade quinn

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 0.10.0 (Debian / Ubuntu)

apt-cache madison quinn sudo apt install quinn=<VERSION_BEFORE_0.10.0> sudo apt-mark hold quinn

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

dnf --showduplicates list quinn sudo dnf downgrade quinn-<VERSION_BEFORE_0.10.0> sudo dnf versionlock add quinn

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-2023-42805?

quinn: upgrade to 0.9.5, 0.10.5. Exact commands for each OS are on this page.

Is CVE-2023-42805 being exploited?

CVE-2023-42805 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-2023-42805 affect?

CVE-2023-42805 affects quinn. Severity is high (CVSS 7.5). quinn-proto is a state machine for the QUIC transport protocol. Prior to versions 0.9.5 and 0.10.5, receiving unknown QUIC frames in a QUIC packet could result in a panic. The problem has been fixed in 0.9.5 and 0.10.5 maintenance releases.

How urgent is CVE-2023-42805?

Priority 46/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2024-45311 HIGH 7.5 UPGRADE Quinn is a pure-Rust, async-compatible implementation of the IETF QUIC transport protocol

References

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