CVE-2018-16985: In Lizard (formerly LZ5) 2.0, use of an invalid memory address was discovered in LZ5_compress_continue in lz5_

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HIGH 7.5REMOTEDOWNGRADE

CVE-2018-16985 is a high-severity flaw (CVSS 7.5) affecting lizard. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Lizard (formerly LZ5) 2.0, use of an invalid memory address was discovered in LZ5_compress_continue in lz5_compress.c, related to LZ5_compress_fastSmall and MEM_read32. The vulnerability causes a segmentation fault and application crash, which leads to denial of service.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 26%)
CISA exploited list	No
Weakness	CWE-125
Published	2018-09-13
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: lizard project

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

Am I affected?

Timeline

2018-09-13 14:29 UTCPublished CVE record published
2026-06-17 01:45 UTCUpdated Record last modified

lizard project lizard DOWNGRADE

Affected: 2.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.0 (Debian / Ubuntu)

apt-cache madison lizard sudo apt install lizard=<VERSION_BEFORE_2.0> sudo apt-mark hold lizard

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list lizard sudo dnf downgrade lizard-<VERSION_BEFORE_2.0> sudo dnf versionlock add lizard

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-2018-16985?

lizard: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-16985 being exploited?

CVE-2018-16985 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-2018-16985 affect?

CVE-2018-16985 affects lizard. Severity is high (CVSS 7.5). In Lizard (formerly LZ5) 2.0, use of an invalid memory address was discovered in LZ5_compress_continue in lz5_compress.c, related to LZ5_compress_fastSmall and MEM_read32. The vulnerability causes a segmentation fault and application crash,

How urgent is CVE-2018-16985?

Priority 55/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2018-11498 HIGH 7.8 DOWNGRADE DOWNGRADE In Lizard v1.0 and LZ5 v2.0 (the prior release, before the product was renamed), there is an unchecked buffer

References

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