CVE•Published 2021-06-02•Modified 2026-10-14•1 article on news•6 live references•NVD data
CVE-2021-3520Lz4_project · Lz4
Vulnerability data via NVD (ingested)
CVSS v3.1
9.8
CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS percentile
88
Exploit Prediction Scoring System · top 12% of all CVEs
Weaknesses (CWE)
Description
There's a flaw in lz4. An attacker who submits a crafted file to an application linked with lz4 may be able to trigger an integer overflow, leading to calling of memmove() on a negative size argument, causing an out-of-bounds write and/or a crash. The greatest impact of this flaw is to availability, with some potential impact to confidentiality and integrity as well.
Timeline
Published 2021-06-02
Modified 2026-10-14
External references
Search for exposed instances
Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).
Shodan · vuln tag0 hosts
vuln:CVE-2021-3520Hosts Shodan has explicitly fingerprinted as vulnerable.
Shodan · product
product:"Lz4 Project Lz4"All exposed Lz4 Project Lz4 instances — cross-reference with the CVE's affected-version range.
Shodan · banner/body mention
http.html:"Lz4"HTTP body or banner mentions "Lz4" — catches deploys Shodan didn't identify as a product.
More intel sources (5)
Shodan report
vuln:CVE-2021-3520Country / ASN / product breakdown for the vuln query.
Censys
vulnerabilities.cve_id: CVE-2021-3520Censys host search filtered to this CVE id.
grep.app
CVE-2021-3520Public source-code mentions — fast PoC discovery.
GitHub code
CVE-2021-3520GitHub code search for direct mentions.
Google dork
"CVE-2021-3520" exploit -site:nvd.nist.govWrite-ups and news, NVD excluded.