MEDIUM
CVE-2021-30501
CWE-20Published: May 27, 2021· Updated: Jun 17, 2026
5.5
CVSS v3.1
Official Description
An assertion abort was found in upx MemBuffer::alloc() in mem.cpp, in version UPX 4.0.0. The flow allows attackers to cause a denial of service (abort) via a crafted file.
Technical Analysis
CVE-2021-30501 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.
A successful exploit results in availability disruption (denial of service), with a CVSS base score of 5.5.
CVSS v3.1 Vector Breakdown
Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Affected Vendors & Products
Exploit & PoC Resources
NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.
Official Patches & Advisories
All References (8)
→
https://bugzilla.redhat.com/show_bug.cgi?id=1948696Issue Tracking · Patch · Third Party Advisory
→
https://github.com/upx/upx/commit/28e761cd42211dfe0124b7a29b2f74730f453e46Patch · Third Party Advisory
→
https://github.com/upx/upx/issues/486Exploit · Issue Tracking · Third Party Advisory
→
https://github.com/upx/upx/pull/487Exploit · Patch · Third Party Advisory
→
https://bugzilla.redhat.com/show_bug.cgi?id=1948696Issue Tracking · Patch · Third Party Advisory
→
https://github.com/upx/upx/commit/28e761cd42211dfe0124b7a29b2f74730f453e46Patch · Third Party Advisory
→
https://github.com/upx/upx/issues/486Exploit · Issue Tracking · Third Party Advisory
→
https://github.com/upx/upx/pull/487Exploit · Patch · Third Party Advisory
Quick Facts
CVE IDCVE-2021-30501
CVSS Score5.5 / 10
SeverityMEDIUM
WeaknessCWE-20
CISA KEVNo
Affected3 vendor(s)
PublishedMay 27, 2021
Related CVEs (CWE-20)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-30501 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.