Bug 2541638 (CVE-2026-6103)

Summary: CVE-2026-6103 php: PHP: Archive entry injection via integer overflow in TAR parser
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in PHP. An integer overflow vulnerability in the Phar extension occurs when parsing TAR archive headers containing excessively large size fields. An attacker can exploit this issue by supplying a specially crafted archive file to an application that processes TAR archives, causing the parser to miscalculate data boundaries and treat file content as valid header data. This allows an attacker to inject unauthorized entries that the application extracts as authentic files, potentially leading to unauthorized data modification.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2552134    
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Description OSIDB Bzimport 2026-09-25 20:41:16 UTC 
phar_tar_number() parses the octal size field of a TAR header into a uint32_t with no overflow check. The field is 11 octal digits wide and holds values up to 0x1FFFFFFFF, so a size above 0xFFFFFFFF silently wraps. The parser then skips the wrong number of data blocks and interprets attacker-controlled file content as the next TAR header, which lets a crafted archive inject entries that PharData reports and extracts as if they were genuine.