CVE-2026-84851Network attack vector

Application crash via unbounded nested-value recursion

Published Sep 2, 2026 · Updated Sep 3, 2026

Uncontrolled recursion in Amazon Ion-C before 1.1.6 allows remote attackers to crash an embedding application via crafted Ion data. The ion_writer_write_one_value and ion_writer_write_all_values APIs automatically rewrite reader data without a default depth limit, so deeply nested values exhaust the native call stack. Exploitation requires an application to pass attacker-controlled Ion input through either API; the bounded consequence is a process crash and service interruption.

CVSS severity8.7
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled recursion in Amazon Ion-C before 1.1.6 allows remote attackers to crash an embedding application via crafted Ion data. The ion_writer_write_one_value and ion_writer_write_all_values APIs automatically rewrite reader data without a default depth limit, so deeply nested values exhaust the native call stack. Exploitation requires an application to pass attacker-controlled Ion input through either API; the bounded consequence is a process crash and service interruption.

The record

CVE
CVE-2026-84851
Published
Sep 2, 2026
Updated
Sep 3, 2026
Vendor
Amazon Ion
Product
ion-c
Classifications
CWE-674, CAPEC-230, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 3, 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 <1.1.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Amazon Ion · ion-cversion=0 <1.1.6

Published CVSS scores

7.5Amazon CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7Amazon CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
CAPEC-230Serialized Data with Nested Payloads
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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