CVE-2020-27788Public exploit

Process crash via unchecked ELF string-table offset

Published Aug 18, 2022 · Updated Aug 4, 2024

Out-of-bounds read in PackLinuxElf64::canPack in UPX before 3.96 allows local users to crash the process with a crafted ELF file. PackLinuxElf64::canPack trusts the ELF section-name offset and passes shstrtab plus that offset to strcmp after checking only the offset against the whole file size, so the comparison can run beyond the mapped input. Local users must cause UPX to pack the crafted 64-bit Linux ELF; the demonstrated consequence is process termination without reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in PackLinuxElf64::canPack in UPX before 3.96 allows local users to crash the process with a crafted ELF file. PackLinuxElf64::canPack trusts the ELF section-name offset and passes shstrtab plus that offset to strcmp after checking only the offset against the whole file size, so the comparison can run beyond the mapped input. Local users must cause UPX to pack the crafted 64-bit Linux ELF; the demonstrated consequence is process termination without reported data disclosure or modification.

The record

CVE
CVE-2020-27788
Published
Aug 18, 2022
Updated
Aug 4, 2024
Vendor
The UPX Team
Product
UPX
Classifications
CWE-125
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 18, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Fixed in v3.96.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The UPX Team · UPXversion=Fixed in v3.96.

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-125Out-of-bounds Read

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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