CVE-2026-39243: n/a
A vulnerability in decompress versions before 4.2.2 allows an attacker to create arbitrary hardlinks during archive extraction. This occurs because the x.linkname field from the archive is used without validation when processing hardlink entries, enabling an attacker to link to any file on the same filesystem. This can lead to unauthorized reading and overwriting of files, causing file disclosure and corruption. The vulnerability is limited to files on the same filesystem and does not affect directories. A patch is available to address this issue.
AI Analysis
Technical Summary
The decompress library before version 4.2.2 contains a vulnerability (CVE-2026-39243) where the x.linkname field in hardlink entries is passed directly to fs.link() without validation. This allows an attacker to craft an archive with a hardlink entry pointing to an absolute path of any file on the same filesystem. During extraction, this creates a hardlink inside the extraction directory that shares the inode with the target file, enabling both reading and overwriting of the original file's content. The vulnerability is classified under CWE-59 (Improper Link Resolution Before File Access).
Potential Impact
Successful exploitation allows an attacker with the ability to supply archive files to cause arbitrary file read disclosure and file corruption on the target system by creating hardlinks to existing files. This can compromise confidentiality and integrity of files on the same filesystem as the extraction directory. The attack requires local access or the ability to influence archive extraction and does not affect availability.
Mitigation Recommendations
A patch is available for decompress that fixes this vulnerability in version 4.2.2. Users should upgrade to version 4.2.2 or later to remediate this issue. Until patched, avoid extracting untrusted archives with decompress or implement additional validation on archive contents to prevent hardlink exploitation.
CVE-2026-39243: n/a
Description
A vulnerability in decompress versions before 4.2.2 allows an attacker to create arbitrary hardlinks during archive extraction. This occurs because the x.linkname field from the archive is used without validation when processing hardlink entries, enabling an attacker to link to any file on the same filesystem. This can lead to unauthorized reading and overwriting of files, causing file disclosure and corruption. The vulnerability is limited to files on the same filesystem and does not affect directories. A patch is available to address this issue.
CVSS v3.1
Score 5.5medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The decompress library before version 4.2.2 contains a vulnerability (CVE-2026-39243) where the x.linkname field in hardlink entries is passed directly to fs.link() without validation. This allows an attacker to craft an archive with a hardlink entry pointing to an absolute path of any file on the same filesystem. During extraction, this creates a hardlink inside the extraction directory that shares the inode with the target file, enabling both reading and overwriting of the original file's content. The vulnerability is classified under CWE-59 (Improper Link Resolution Before File Access).
Potential Impact
Successful exploitation allows an attacker with the ability to supply archive files to cause arbitrary file read disclosure and file corruption on the target system by creating hardlinks to existing files. This can compromise confidentiality and integrity of files on the same filesystem as the extraction directory. The attack requires local access or the ability to influence archive extraction and does not affect availability.
Mitigation Recommendations
A patch is available for decompress that fixes this vulnerability in version 4.2.2. Users should upgrade to version 4.2.2 or later to remediate this issue. Until patched, avoid extracting untrusted archives with decompress or implement additional validation on archive contents to prevent hardlink exploitation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- mitre
- Date Reserved
- 2026-04-06T00:00:00.000Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a50171468715ace431ea188
Added to database: 07/09/2026, 21:48:04 UTC
Last enriched: 08/13/2026, 18:10:06 UTC
Last updated: 08/23/2026, 23:41:37 UTC
Views: 66
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