Upx
CVE-2021-30500
HIGH
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A10:2025 - Mishandling of Exceptional Conditions
ASVS 5.0
V16 - Security Logging and Error Handling Null pointer safety, defensive checks
MITRE ATT&CK
1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 7.8 (HIGH). Attack characteristics: local attack vector, low complexity, no privileges required, user interaction required. Public proof-of-concept exploit code is available. |
| Exploit ScenarioDerived | A local attacker with access to the system could crash the application by dereferencing a null pointer. No authentication is required to exploit this vulnerability. |
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Alert meAnalysisAI
Null pointer dereference was found in upx PackLinuxElf::canUnpack() in p_lx_elf.cpp,in version UPX 4.0.0. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity. Public exploit code available.
RemediationAI
A vendor patch is available. Apply the latest security update as soon as possible. Check pointers before dereferencing. Use static analysis tools to detect null pointer paths.
Affects your stack
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Technical ContextAI · show details
This vulnerability is classified as NULL Pointer Dereference (CWE-476), which allows attackers to crash the application by dereferencing a null pointer. Null pointer dereference was found in upx PackLinuxElf::canUnpack() in p_lx_elf.cpp,in version UPX 4.0.0. That allow attackers to execute arbitrary code and cause a denial of service via a crafted file. Affected products include: Upx, Redhat Enterprise Linux, Fedoraproject Fedora.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
Null pointer dereference was found in upx PackLinuxElf::canUnpack() in p_lx_elf.cpp,in version UPX 4.0.0. That allow attackers to execute arbitrary code and cause a denial of service via a crafted file.
Threat Intelligence Overview
NVD
CVE.org
EPSS
GitHub
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
A null pointer dereference occurs when a program attempts to access memory through a pointer that has been set to NULL (address 0x0).
Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.
Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.
Affected Products (CPE)NVD
A vulnerability was found in UPX up to 4.2.2. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploit
canUnpack in p_vmlinx.cpp in UPX 3.95 allows remote attackers to cause a denial of service (SEGV or buffer overflow, and
PackLinuxElf64::unpack in p_lx_elf.cpp in UPX 3.95 allows remote attackers to cause a denial of service (double free), l
A flaw was found in upx canPack in p_lx_elf.cpp in UPX 3.96. Rated medium severity (CVSS 6.6), this vulnerability is no
A Segmentation fault was found in UPX in PackLinuxElf64::invert_pt_dynamic() in p_lx_elf.cpp. Rated medium severity (CVS
A heap-based buffer overflow issue was discovered in UPX in PackTmt::pack() in p_tmt.cpp file. Rated medium severity (CV
An assertion abort was found in upx MemBuffer::alloc() in mem.cpp, in version UPX 4.0.0. Rated medium severity (CVSS 5.5
An invalid memory address dereference was discovered in the canUnpack function in p_mach.cpp in UPX 3.95 via a crafted M
A floating-point exception was discovered in PackLinuxElf::elf_hash in p_lx_elf.cpp in UPX 3.95. Rated medium severity (
A heap-based buffer over-read was discovered in canUnpack in p_mach.cpp in UPX 3.95 via a crafted Mach-O file. Rated med
An Integer overflow in the getElfSections function in p_vmlinx.cpp in UPX 3.95 allows remote attackers to cause a denial
A vulnerability, which was classified as problematic, was found in UPX up to 5.0.0. Rated medium severity (CVSS 4.8), th
Exploit-DB