CVE-2026-55497Public exploitNetwork attack vector

Server crash via unbounded image pixel allocation

Published Jul 31, 2026 · Updated Jul 31, 2026

Uncontrolled resource consumption in Cloudreve before 4.17.0 allows remote authenticated users to crash the server with a crafted image. NewThumbFromFile passes PNG, JPEG, and GIF headers to Go decoders without checking pixel dimensions, so header values drive an unbounded pixel-buffer allocation. Any registered user can reach the synchronous avatar path, and default thumbnail generation can re-trigger a stored bomb after the process restarts.

CVSS severity6.5
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Cloudreve before 4.17.0 allows remote authenticated users to crash the server with a crafted image. NewThumbFromFile passes PNG, JPEG, and GIF headers to Go decoders without checking pixel dimensions, so header values drive an unbounded pixel-buffer allocation. Any registered user can reach the synchronous avatar path, and default thumbnail generation can re-trigger a stored bomb after the process restarts.

The record

CVE
CVE-2026-55497
Published
Jul 31, 2026
Updated
Jul 31, 2026
Vendor
Cloudreve
Product
Cloudreve
Classifications
CWE-770, CWE-400, CWE-409, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 31, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 31, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 4.17.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Cloudreve · Cloudreveversion=< 4.17.0

Published CVSS scores

6.5GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-400Uncontrolled Resource Consumption
CWE-409Improper Handling of Highly Compressed Data (Data Amplification)
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

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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