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CVE-2026-59933— PhpSpreadsheet: XLS/OLE sector-chain self-loop causes memory exhaustion

Quick assessment

Affected
PHPOffice PhpSpreadsheet
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

PHPOffice PhpSpreadsheet是PHPOffice组织开源的一款用于读取和写入电子表格文件的PHP库。 PHPOffice PhpSpreadsheet 4.0.0版本至5.8.0版本、3.3.0版本至3.10.6版本、2.2.0版本至2.4.6版本、2.0.0版本至2.1.17版本和1.30.5及之前版本存在资源管理错误漏洞，该漏洞源于OLE reader遵循攻击者控制的XLS/OLE元数据中的扇区链，未检测循环或强制最大链长度，导致无限循环消耗内存，造成拒绝服务。

CVSS 7.5 · High EPSS 0.70% · P52

Affected Version Matrix 5

VendorProduct Version RangeStatus
PHPOffice PhpSpreadsheet >= 4.0.0, < 5.8.1 affected
>= 3.3.0, < 3.10.7 affected
>= 2.2.0, < 2.4.7 affected
>= 2.0.0, < 2.1.18 affected
< 1.30.6 affected
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I. Basic Information for CVE-2026-59933

Vulnerability Information
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Vulnerability Title
PhpSpreadsheet: XLS/OLE sector-chain self-loop causes memory exhaustion
Source: CVE Program / CVE List V5
Vulnerability Description
PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. In versions 4.0.0 through 5.8.0, 3.3.0 through 3.10.6, 2.2.0 through 2.4.6, 2.0.0 through 2.1.17, and all releases up to and including 1.30.5, the OLE reader follows sector chains from attacker-controlled XLS/OLE metadata without detecting cycles or enforcing a maximum chain length. A tiny malformed .xls/OLE file can set the small-block depot sector chain to point back to itself. During normal XLS detection, OLERead::read() appends the same sector data repeatedly until the PHP process exhausts memory. This is reachable from Reader\Xls::canRead() and therefore from automatic spreadsheet type detection. Applications that accept attacker-controlled spreadsheet uploads can suffer denial of service from a very small file. This issue has been fixed in versions 5.8.1, 3.10.7, 2.4.7, 2.1.18 and 1.30.6.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
PHPOffice PhpSpreadsheet 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
PHPOffice PhpSpreadsheet是PHPOffice组织开源的一款用于读取和写入电子表格文件的PHP库。 PHPOffice PhpSpreadsheet 4.0.0版本至5.8.0版本、3.3.0版本至3.10.6版本、2.2.0版本至2.4.6版本、2.0.0版本至2.1.17版本和1.30.5及之前版本存在资源管理错误漏洞，该漏洞源于OLE reader遵循攻击者控制的XLS/OLE元数据中的扇区链，未检测循环或强制最大链长度，导致无限循环消耗内存，造成拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
PHPOffice PhpSpreadsheet >= 4.0.0, < 5.8.1 -

II. Public POCs for CVE-2026-59933

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 12779 chars
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III. Intelligence Information for CVE-2026-59933

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Patches & Fixes for CVE-2026-59933 (1)

Vendor Advisories for CVE-2026-59933 (1)

Vendor Pages for CVE-2026-59933 (5)

Same Patch Batch · PHPOffice · 2026-07-28 · 3 CVEs total

CVE-2026-59931 7.7 HIGH PhpSpreadsheet: SSRF bypass via HTTP redirect in WEBSERVICE() domain whitelist
CVE-2026-59932 7.5 HIGH PhpSpreadsheet: Gnumeric reader unbounded gzip expansion causes memory exhaustion

IV. Related Vulnerabilities

Same product: PhpSpreadsheet
Same vendor: PHPOffice
Same weakness: CWE-400

V. Comments for CVE-2026-59933

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