A heap buffer overflow read was discovered in upx 4.0.0, because the check in p_lx_elf.cpp is not perfect.
An official patch is available. Apply the patch as soon as possible.
CVSS v4.0 Metrics
Exploitability
Attack VectorLocal
ComplexityLow
RequirementsPresent
PrivilegesNone
User InteractionActive
Threat
Exploit MaturityPoC
Vulnerable System
ConfidentialityHigh
IntegrityNone
AvailabilityHigh
Subsequent System
ConfidentialityNone
IntegrityNone
AvailabilityNone
Supplemental
SafetyNegligible
AutomatableYes
RecoveryAutomatic
Value DensityConcentrated
UrgencyMedium
Patch StatusOfficial Patch
Change Log
| Date | Source | Changes | Score |
|---|
| 2026-07-21 | PoC | E: U→P | 1.7 → 4.6 |
| 2026-07-21 | nvd | AV: P→L, AC: H→L, PR: H→N, VC: N→H, VA: N→H | 0.0 → 1.7 |
| 2026-07-21 | nvd | patch: Unavailable→Official Patch | 0.0 → 0.0 |
| 2026-07-21 | cve.org | initial, patch: Unavailable | 0.0 |
Affected Software
| Vendor | Product | Version |
|---|
| fedoraproject | fedora | 33 |
| fedoraproject | fedora | 34 |
| upx | upx | 4.0.0 |
Published: 2021-05-14
