CVE-2026-23879Public exploitNetwork attack vector

Arbitrary file write via unresolved symlink chains

Published Jun 24, 2026 · Updated Jun 24, 2026

Improper link resolution in Hiroshi Miura py7zr 1.1.2 and earlier allows attackers to write arbitrary files via crafted archives. The extractall path check validates each link arcname inside the destination but never resolves the full chain before restoring symlinks. A user or application must extract an attacker-supplied archive, after which regular files can escape through the restored chain and overwrite paths writable by the extracting process.

CVSS severity8.0
High
EPSS probability0.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper link resolution in Hiroshi Miura py7zr 1.1.2 and earlier allows attackers to write arbitrary files via crafted archives. The extractall path check validates each link arcname inside the destination but never resolves the full chain before restoring symlinks. A user or application must extract an attacker-supplied archive, after which regular files can escape through the restored chain and overwrite paths writable by the extracting process.

The record

CVE
CVE-2026-23879
Published
Jun 24, 2026
Updated
Jun 24, 2026
Vendor
Hiroshi Miura
Product
py7zr
Classifications
CWE-59, T1204.002, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 24, 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 privilegesauthenticated

What is affected?

Hiroshi Miura · py7zrversion=< 1.1.3

Published CVSS scores

8.0GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')
T1204.002User Execution: Malicious File
T1203Exploitation for Client Execution

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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