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Fencer Vulns
medium 5.3

CVE-2023-23456 json

Upx: heap-buffer-overflow in packtmt::pack()

published 2023-01-12 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-27556

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

A heap-based buffer overflow issue was discovered in UPX in PackTmt::pack() in p_tmt.cpp file. The flow allows an attacker to cause a denial of service (abort) via a crafted file.

Patch / fix

  • upx upx 2022-11-24
  • upx-ucl Debian 14, Debian 13 4.2.2-1

debian advisories DEBIAN-CVE-2023-23456

  • upx Package Hub 15 SP4, openSUSE Leap 15.4 4.0.2-bp154.4.6.1

opensuse advisories openSUSE-SU-2023:0088-1

  • upx Alpine 3.24, Alpine 3.23, Alpine 3.22 +5 more 4.0.2-r0

alpine advisories ALPINE-CVE-2023-23456

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

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-23456 updated cvss 5.3

upx: heap-buffer-overflow in PackTmt::pack()

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/upx/upx/issues/632 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Classification

Weakness

References

Sources

Fencer Vulns 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.