Bug 2498833 (CVE-2026-39243)

Summary: CVE-2026-39243 decompress: Decompress: File disclosure and corruption via arbitrary hardlink creation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: aschwart, aszczucz, boliveir, drichtar, gparvin, mposolda, pjindal, rhaigner, rmartinc, ssilvert, sthorger, vmuzikar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in decompress. An attacker can craft a malicious archive that, when extracted, allows for arbitrary hardlink creation. This vulnerability occurs because the x.linkname field from hardlink entries in the archive is processed without proper validation, enabling an attacker to create a hardlink to any file on the same filesystem. This could lead to sensitive file read disclosure or file corruption on the system.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2507934, 2507935    
Bug Blocks:    

Description OSIDB Bzimport 2026-07-09 22:03:05 UTC 
decompress before 4.2.2 allows arbitrary hardlink creation during archive extraction, enabling file read disclosure and file corruption. When processing hardlink entries (type === 'link'), the x.linkname field from the archive is passed directly to fs.link() without validation (index.js line 113). An attacker can craft an archive with a hardlink entry whose linkname is an absolute path to any file on the same filesystem. This creates a hardlink inside the extraction directory that shares the same inode as the target file, enabling both reading and overwriting the original file's content. Hardlinks are limited to files on the same filesystem and cannot target directories.