CVE-2021-3520
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…
- Published
- Updated
- Reserved
- Assigned by
- redhat
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
ID reserved
By redhat
- 35 days later
· 35 days later
Published
- 5 years later
· 5 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 3.4% · top 11% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Weakness
Affected products
lz4
- affected lz4-1.8.3
References (6)
- https://bugzilla.redhat.com/show_bug.cgi?id=1954559 (opens in a new tab)x_refsource_MISCx_transferred
- https://www.oracle.com//security-alerts/cpujul2021.html (opens in a new tab)x_refsource_MISCx_transferred
- https://www.oracle.com/security-alerts/cpuoct2021.html (opens in a new tab)x_refsource_MISCx_transferred
- https://www.oracle.com/security-alerts/cpuapr2022.html (opens in a new tab)x_refsource_MISCx_transferred
- https://security.netapp.com/advisory/ntap-20211104-0005/ (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-3520)Record last updated .