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Fencer Vulns
high 7.5

CVE-2021-43317 json

A heap-based buffer overflows was discovered in upx, during the generic pointer 'p' points to an inaccessible address in func get_le32().

published 2023-03-24 3 y ago modified 2026-06-17 4 mo ago also EUVD-2021-30256

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

A heap-based buffer overflows was discovered in upx, during the generic pointer 'p' points to an inaccessible address in func get_le32(). The problem is essentially caused in PackLinuxElf64::elf_lookup() at p_lx_elf.cpp:5404

Patch / fix

  • upx upx 4.0.0
  • upx-ucl Debian 14, Debian 13 4.2.2-1

debian advisories DEBIAN-CVE-2021-43317

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

opensuse advisories openSUSE-SU-2023:0088-1

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-2021-43317 updated cvss 5.3

upx: heap-based buffer overflow in PackLinuxElf64::elf_lookup() at p_lx_elf.cpp

  • 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
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
20 mo ago

Exploit prediction

0.82% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/upx/upx/issues/380 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • n/a upx

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
  • CWE-787 Out-of-bounds Write

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.