CVE-2026-18929Network attack vector

Server crash via .docx zip bomb

Published Aug 18, 2026 · Updated Aug 18, 2026

Denial of service in Carbone before 3.8.2, 4.26.3, and 5.4.4 allows remote attackers to crash the server via a crafted .docx file. In lib/file.js, Carbone processes ZIP-based DOCX templates without safely bounding decompression; the fix enables entry-size validation and rejects archives whose total expanded size exceeds a configured limit. Exploitation requires the application to accept attacker-supplied DOCX templates for server-side processing, and the documented impact is memory exhaustion and application unavailability rather than data access or code execution.

CVSS severity6.9
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Carbone before 3.8.2, 4.26.3, and 5.4.4 allows remote attackers to crash the server via a crafted .docx file. In lib/file.js, Carbone processes ZIP-based DOCX templates without safely bounding decompression; the fix enables entry-size validation and rejects archives whose total expanded size exceeds a configured limit. Exploitation requires the application to accept attacker-supplied DOCX templates for server-side processing, and the documented impact is memory exhaustion and application unavailability rather than data access or code execution.

The record

CVE
CVE-2026-18929
Published
Aug 18, 2026
Updated
Aug 18, 2026
Vendor
CarboneIO
Product
Carbone
Classifications
CWE-409, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.8.2
  2. Affected versionversion=0 <4.26.3
  3. Affected versionversion=0 <5.4.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

CarboneIO · Carboneversion=0 <3.8.2; version=0 <4.26.3; version=0 <5.4.4

Published CVSS scores

6.9CERT-PLCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-409Improper Handling of Highly Compressed Data (Data Amplification)
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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