Security readout for executives and security teams
Plain-English summary
CVE-2020-27799 is a memory safety issue in UPX where a specially crafted Mach-O file can cause a heap buffer over-read. The source bundle does not provide a CVSS score, confirmed impact, or patch details, so business urgency depends on whether affected UPX builds process untrusted Mach-O files.
Executive priority
Treat this as a targeted tooling exposure, not a broad enterprise emergency, unless affected UPX versions process untrusted Mach-O files. Validate exposure first, then isolate or update based on vendor guidance.
Technical view
The flaw is a heap-based buffer over-read in acc_ua_get_be32 within miniacc.h in UPX 4.0.0-git-87b73e5cfdc1+. It is associated with CWE-119 and is triggered through crafted Mach-O input. No exploit status, CVSS vector, or remediation version is provided in the bundle.
Likely exposure
Exposure appears limited to environments running the listed affected UPX build and processing Mach-O files. Risk is higher where UPX handles untrusted files in build, analysis, or automation workflows.
Exploitation context
The source bundle does not cite active exploitation, and the CVE is not marked as CISA KEV. The only supported trigger context is a crafted Mach-O file.
Researcher notes
Evidence is sparse: the CVE record identifies function, file, affected build, and crafted Mach-O trigger, but no CVSS, exploit evidence, patch version, or detailed impact. Avoid assuming code execution or active exploitation without stronger sources.
Mitigation direction
- Inventory UPX versions in developer, build, and analysis environments.
- Avoid processing untrusted Mach-O files with the affected UPX build.
- Check UPX vendor guidance and the referenced issue for fixed versions.
- Prioritize replacement or isolation where UPX handles external file input.
Validation and detection
- Confirm whether UPX 4.0.0-git-87b73e5cfdc1+ is installed or embedded.
- Identify workflows that pass Mach-O files to UPX.
- Review logs or pipelines for automated UPX processing of external files.
- Track the referenced UPX issue for authoritative remediation status.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-119: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2020-27799 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/upx/upx/issues/391CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Restriction of Operations within the Bounds of a Memory Buffer
Improper Restriction of Operations within the Bounds of a Memory Buffer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.