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CVE-2026-78206— exceljs through 4.4.0 Uncontrolled Resource Consumption via Unbounded xlsx Decompression

Quick assessment

Affected
exceljs exceljs
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.

exceljs是exceljs组织的一款读取和写入Excel文件的JavaScript库。 exceljs 5.0.0之前版本存在资源管理错误漏洞，该漏洞源于未限制解压条目大小、总大小或压缩比，导致攻击者可以上传高度压缩的工作簿，在内存中扩展到GB级，耗尽资源，造成拒绝服务。

CVSS 7.5 · High EPSS 0.63% · P49

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

Affected Version Matrix 1

VendorProduct Version RangeStatus
exceljs exceljs ≤ 4.4.0 affected
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I. Basic Information for CVE-2026-78206

Vulnerability Information
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Vulnerability Title
exceljs through 4.4.0 Uncontrolled Resource Consumption via Unbounded xlsx Decompression
Source: CVE Program / CVE List V5
Vulnerability Description
exceljs through 4.4.0 decompresses all entries from supplied xlsx archives into memory without limits on entry size, total size, or compression ratio. Attackers can upload highly compressed workbooks that expand to gigabytes in memory, exhausting available resources and causing denial of service.
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
对高度压缩数据的处理不恰当(数据放大攻击)
Source: CVE Program / CVE List V5
Vulnerability Title
exceljs 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
exceljs是exceljs组织的一款读取和写入Excel文件的JavaScript库。 exceljs 5.0.0之前版本存在资源管理错误漏洞，该漏洞源于未限制解压条目大小、总大小或压缩比，导致攻击者可以上传高度压缩的工作簿，在内存中扩展到GB级，耗尽资源，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
exceljs exceljs 0 ~ 4.4.0 -

II. Public POCs for CVE-2026-78206

# POC Description Source Link Shenlong Link
AI-Generated POC Verified env Premium
Reproduced successfully in a real sandbox · Below is the actual recording of building the environment and exploiting the vulnerability.
Success marker: VULNERABLE: unbounded xlsx decompression DoS — RSS grew by 612 MB (bomb expanded 300 MB) proof token: PROOF_a65d8604f3ac155b
Reproduction recording is a Pro+ exclusive
Watch the full sandbox build + live exploit recording for this CVE. Limited-time ¥499/mo.
Upgrade to Pro+
claude_code · 8406 chars
GitHub 复现环境（可 clone 直接跑）
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
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III. Intelligence Information for CVE-2026-78206

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Patches & Fixes for CVE-2026-78206 (1)

Vendor Advisories for CVE-2026-78206 (2)

Same Patch Batch · exceljs · 2026-08-24 · 4 CVEs total

CVE-2026-78207 9.4 CRITICAL exceljs through 4.4.0 Prototype Pollution via deepMerge Reached From Note Serialization
CVE-2026-78209 8.2 HIGH exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values
CVE-2026-78208 7.5 HIGH exceljs through 4.4.0 Path Traversal via Unvalidated addImage filename

IV. Related Vulnerabilities

Same product: exceljs
Same vendor: exceljs
Same weakness: CWE-409

V. Comments for CVE-2026-78206

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