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CVE-2026-6103— Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection

Quick assessment

Affected
PHP Group PHP
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

phar_tar_number() 函数在解析 TAR 头部的八进制大小字段时，将其转换为 uint32_t 类型，但未进行溢出检查。该字段宽度为 11 个八进制位，可表示的最大值为 0x1FFFFFFFF；因此，当实际大小超过 0xFFFFFFFF 时，会发生静默截断（回绕）。解析器随后会错误地跳过相应数量的数据块，并将攻击者控制的文件内容误解释为下一个 TAR 头部。这种漏洞使得恶意构造的归档文件能够注入伪造的条目，导致 PharData 将这些条目报告并提取为合法内容，从而产生安全风险。

CVSS 4.3 · Medium EPSS 0.17% · P5

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-6103

Vulnerability Information
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Vulnerability Title
Phar TAR phar_tar_number() Integer Overflow - Archive Entry Injection
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
整数溢出或超界折返
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
PHP Group PHP 8.2.* ~ 8.2.34 -

II. Public POCs for CVE-2026-6103

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III. Intelligence Information for CVE-2026-6103

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Vendor Advisories for CVE-2026-6103 (1)

Same Patch Batch · PHP Group · 2026-09-25 · 11 CVEs total

CVE-2026-91765 7.5 HIGH SOAP: Unbounded Recursion in Server-Side cleanup_xml_node
CVE-2026-17545 6.9 MEDIUM PHP on Windows: Reserved Device Names Are Not Rejected Before File/Stream I/O which can ca
CVE-2026-91767 6.5 MEDIUM Heap-buffer-overflow in php_openssl_matches_wildcard_name on crafted server cert wildcard
CVE-2026-91768 6.5 MEDIUM IPv6 ACL bypass in FastCGI listen.allowed_clients due to partial address comparison (memcm
CVE-2025-14181 6.5 MEDIUM Integer overflow to buffer overflow in soap HTTP parsing
CVE-2026-92842 5.9 MEDIUM OOB read / info leak in convert.* stream filters when line-break-chars contains NUL
CVE-2026-91766 5.9 MEDIUM Cross-origin credential leak in HTTP stream wrapper redirects
CVE-2026-93682 5.8 MEDIUM Out-of-bounds read in the HTTP stream wrapper when following a redirect with an empty Loca
CVE-2026-91769 4.3 MEDIUM TLS Hostname Verification Falls Back to CN After SAN Mismatch
CVE-2025-1218 3.4 LOW Various packet overreads in mysqlnd_writeprotocol.c

IV. Related Vulnerabilities

Same product: PHP
Same vendor: PHP Group
Same weakness: CWE-190

V. Comments for CVE-2026-6103

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