CVE-2018-6343: Proxygen fails to validate that a secondary auth manager is set before dereferencing it

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HIGH 7.5REMOTEUPGRADE

CVE-2018-6343 is a high-severity flaw (CVSS 7.5) affecting proxygen. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Proxygen fails to validate that a secondary auth manager is set before dereferencing it. That can cause a denial of service issue when parsing a Certificate/CertificateRequest HTTP2 Frame over a fizz (TLS 1.3) transport. This issue affects Proxygen releases starting from v2018.10.29.00 until the fix in v2018.11.19.00.

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	0.8% (top 42%)
CISA exploited list	No
Weakness	CWE-476, CWE-20
Published	2018-12-31
Last modified	2026-06-17

Publisher (CNA): Facebook, Inc. · Vendor: facebook

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

Am I affected?

Timeline

2018-12-31 22:29 UTCPublished CVE record published
2026-06-17 02:01 UTCUpdated Record last modified

facebook proxygen UPGRADE

Affected: >= 2018.10.29.00 and < 2018.11.19.00

Fixed in: 2018.11.19.00

Safe to downgrade to: a release before 2018.10.29.00

1. Check installed version

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

2. UPGRADE to 2018.11.19.00 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade proxygen

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 2018.10.29.00 (Debian / Ubuntu)

apt-cache madison proxygen sudo apt install proxygen=<VERSION_BEFORE_2018.10.29.00> sudo apt-mark hold proxygen

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

dnf --showduplicates list proxygen sudo dnf downgrade proxygen-<VERSION_BEFORE_2018.10.29.00> sudo dnf versionlock add proxygen

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-2018-6343?

proxygen: upgrade to 2018.11.19.00. Exact commands for each OS are on this page.

Is CVE-2018-6343 being exploited?

CVE-2018-6343 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-2018-6343 affect?

CVE-2018-6343 affects proxygen. Severity is high (CVSS 7.5). Proxygen fails to validate that a secondary auth manager is set before dereferencing it. That can cause a denial of service issue when parsing a Certificate/CertificateRequest HTTP2 Frame over a fizz (TLS 1.3) transport. This issue affects

How urgent is CVE-2018-6343?

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

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References

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