CVE-2019-17543: LZ4 before 1.9.2 has a heap-based buffer overflow in LZ4_write32 (related to LZ4_compress_destSize), affecting

Q: How do I fix CVE-2019-17543?

lz4: upgrade to 1.9.2. Exact commands for each OS are on this page.

Q: Is CVE-2019-17543 being exploited?

CVE-2019-17543 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2019-17543 affect?

CVE-2019-17543 affects lz4. Severity is high (CVSS 8.1). LZ4 before 1.9.2 has a heap-based buffer overflow in LZ4_write32 (related to LZ4_compress_destSize), affecting applications that call LZ4_compress_fast with a large input. (This issue can also lead to data corruption.) NOTE: the vendor stat

Q: How urgent is CVE-2019-17543?

Priority 57/100. High severity; EPSS top 4%: very likely to be exploited; Remotely exploitable, no login, no user action

This week

HIGH 8.1REMOTEUPGRADE

CVE-2019-17543 is a high-severity flaw (CVSS 8.1) affecting lz4. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

LZ4 before 1.9.2 has a heap-based buffer overflow in LZ4_write32 (related to LZ4_compress_destSize), affecting applications that call LZ4_compress_fast with a large input. (This issue can also lead to data corruption.) NOTE: the vendor states "only a few specific / uncommon usages of the API are at risk."

Why this priority

High severity
EPSS top 4%: very likely to be exploited
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	10.5% (top 4%)
CISA exploited list	No
Weakness	CWE-787
Published	2019-10-14
Last modified	2026-10-14

Publisher (CNA): MITRE · Vendor: lz4 project

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-10-14 02:15 UTCPublished CVE record published
2026-10-14 07:16 UTCUpdated Record last modified

lz4 project lz4 UPGRADE

Affected: < 1.9.2

Fixed in: 1.9.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy lz4 || rpm -q lz4 || lz4 --version

2. UPGRADE to 1.9.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade lz4

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade lz4

Note

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

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-2019-17543?

lz4: upgrade to 1.9.2. Exact commands for each OS are on this page.

Is CVE-2019-17543 being exploited?

CVE-2019-17543 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-2019-17543 affect?

CVE-2019-17543 affects lz4. Severity is high (CVSS 8.1). LZ4 before 1.9.2 has a heap-based buffer overflow in LZ4_write32 (related to LZ4_compress_destSize), affecting applications that call LZ4_compress_fast with a large input. (This issue can also lead to data corruption.) NOTE: the vendor stat

How urgent is CVE-2019-17543?

Priority 57/100. High severity; EPSS top 4%: very likely to be exploited; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-3520 CRITICAL 9.8 UPGRADE MITIGATE There's a flaw in lz4
CVE-2014-4715 MEDIUM 5.0 UPGRADE Yann Collet LZ4 before r119, when used on certain 32-bit platforms that allocate memory beyond 0x80000000, doe

References

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