CVE-2026-45380Public exploit

Parent-directory file write via null-byte symlink traversal

Published Jun 10, 2026 · Updated Jun 10, 2026

Path traversal in bit7z before 4.0.12 allows attackers to write files above an extraction directory through a crafted .7z archive. SafeOutPathBuilder::restoreSymlink() resizes a symlink target to gcount(), retaining a null byte that makes C++ validation see a safe name while POSIX symlink() resolves the truncated target as the parent directory. Exploitation requires a crafted archive to be extracted on Linux, macOS, or BSD; writes are limited to one directory level above the output and inherit the extracting process permissions.

CVSS severity3.6
Low
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in bit7z before 4.0.12 allows attackers to write files above an extraction directory through a crafted .7z archive. SafeOutPathBuilder::restoreSymlink() resizes a symlink target to gcount(), retaining a null byte that makes C++ validation see a safe name while POSIX symlink() resolves the truncated target as the parent directory. Exploitation requires a crafted archive to be extracted on Linux, macOS, or BSD; writes are limited to one directory level above the output and inherit the extracting process permissions.

The record

CVE
CVE-2026-45380
Published
Jun 10, 2026
Updated
Jun 10, 2026
Vendor
Riccardo Ostani
Product
bit7z
Classifications
CWE-22, CWE-193, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 10, 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=< 4.0.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Riccardo Ostani · bit7zversion=< 4.0.12

Published CVSS scores

3.6GitHub, Inc.CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:L

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-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-193Off-by-one Error
T1204.002Malicious File

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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