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Fencer Intel
high 7.8

CVE-2020-27801 json

A heap-based buffer over-read was discovered in the get_le64 function in bele.h in UPX 4.0.0 via a crafted Mach-O file.

published 4y ago modified 4mo ago also EUVD-2020-20303

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits
0
none known

Summary

A heap-based buffer over-read was discovered in the get_le64 function in bele.h in UPX 4.0.0 via a crafted Mach-O file.

Patch / fix

  • upx-ucl Debian 14, Debian 13 4.2.2-1

debian advisories DEBIAN-CVE-2020-27801

  • upx Alpine 3.24, Alpine 3.23, Alpine 3.22 +5 more 4.0.0-r0

alpine advisories ALPINE-CVE-2020-27801

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/upx/upx/issues/394 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • n/a upx

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
  • CWE-125 Out-of-bounds Read

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.