CVE-2026-55195Public exploitNetwork attack vector

Denial of service via unchecked extraction size

Published Jul 8, 2026 · Updated Jul 8, 2026

Data amplification in py7zr before 1.1.3 allows remote attackers to exhaust disk or memory by supplying a crafted 7z archive. Worker.decompress writes decompressed chunks without tracking cumulative output or enforcing a configurable size limit. Exploitation requires the archive to reach an extraction path, and resource exhaustion can interrupt that process or its host.

CVSS severity8.7
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Data amplification in py7zr before 1.1.3 allows remote attackers to exhaust disk or memory by supplying a crafted 7z archive. Worker.decompress writes decompressed chunks without tracking cumulative output or enforcing a configurable size limit. Exploitation requires the archive to reach an extraction path, and resource exhaustion can interrupt that process or its host.

The record

CVE
CVE-2026-55195
Published
Jul 8, 2026
Updated
Jul 8, 2026
Vendor
Hiroshi Miura
Product
py7zr
Classifications
CWE-409, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 8, 2026Record 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=< 1.1.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hiroshi Miura · py7zrversion=< 1.1.3

Published CVSS scores

6.9GitHub Advisory DatabaseCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
8.7GitHub CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-409Improper Handling of Highly Compressed Data (Data Amplification)
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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