CVE-2025-3857Network attack vector

Application hang via unchecked zero-byte stream reads

Published Apr 21, 2025 · Updated Oct 14, 2025

Denial of service in Amazon Ion .NET before 1.3.1 allows remote attackers to hang consuming applications via truncated binary Ion data. RawBinaryReader.ReadAll fails to reject an underlying stream read that returns zero bytes, so its remaining-length loop never advances. Exploitation requires an application to pass attacker-controlled malformed or truncated binary Ion data to the reader, consuming a processing thread indefinitely.

CVSS severity8.7
High
EPSS probability0.59%
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 Amazon Ion .NET before 1.3.1 allows remote attackers to hang consuming applications via truncated binary Ion data. RawBinaryReader.ReadAll fails to reject an underlying stream read that returns zero bytes, so its remaining-length loop never advances. Exploitation requires an application to pass attacker-controlled malformed or truncated binary Ion data to the reader, consuming a processing thread indefinitely.

The record

CVE
CVE-2025-3857
Published
Apr 21, 2025
Updated
Oct 14, 2025
Vendor
Amazon Ion
Product
Ion .NET
Classifications
CWE-835, CWE-502, CAPEC-153, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 21, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 14, 2025Record 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 <1.3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Amazon Ion · Ion .NETversion=0 <1.3.1

Published CVSS scores

8.7AmazonCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5AmazonCVSS:3.1/AV:N/AC:L/PR:N/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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
CWE-502Deserialization of Untrusted Data
CAPEC-153Input Data Manipulation
T1499.004Application or System Exploitation

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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