CVE-2020-18442Public exploit

Application hang via unchecked negative read result

Published Jun 18, 2021 · Updated Aug 4, 2024

Infinite loop in zziplib 0.13.69 allows local users to hang ZIP-processing applications through a malformed ZIP archive. In bins/unzzipcat-zip.c, unzzip_cat_file treats the -1 error return from zzip_file_read as true and passes that negative length to fwrite before repeating. The loop persists when malformed archive data triggers the read error, consuming CPU and leaving the command or embedding application unresponsive.

CVSS severity3.3
Low
EPSS probability0.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Infinite loop in zziplib 0.13.69 allows local users to hang ZIP-processing applications through a malformed ZIP archive. In bins/unzzipcat-zip.c, unzzip_cat_file treats the -1 error return from zzip_file_read as true and passes that negative length to fwrite before repeating. The loop persists when malformed archive data triggers the read error, consuming CPU and leaving the command or embedding application unresponsive.

The record

CVE
CVE-2020-18442
Published
Jun 18, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-835, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 18, 2021CVE 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

3.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499Endpoint Denial of Service

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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