CVE-2021-20285: upx
Vulnerability summary
CVE-2021-20285 is a high (CVSS 8.3) vulnerability in upx. EPSS estimates a 0.75% chance of exploitation in the next 30 days, higher than 54.4% of scored vulnerabilities. 1 public exploit is recorded.
Advisory lineage
Upstream 0 · Downstream 2 · Related 1Timeline
- 26-03-2021PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
Description
A flaw was found in upx canPack in p_lx_elf.cpp in UPX 3.96. This flaw allows attackers to cause a denial of service (SEGV or buffer overflow and application crash) or possibly have unspecified other impacts via a crafted ELF. The highest threat from this vulnerability is to system availability.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · DebianEcosystem advisory · calculated6.6MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
- NVDNIST6.6MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
EPSS trend
Probability
0.75%
Chance of exploitation in the next 30 days
Percentile
54%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.75% on 22-09-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundUpx
Maturity: poc
Weaknesses
CWE · root cause- CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferThe product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
- CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
Affected systems
Debian1 product
- upx-ucl< 4.2.2-1
Ubuntu1 product
- upx-uclAll versions (No fix recorded)
Upx1 product
- upx3.96
3 vendors · 3 products
