CVE-2026-85786

High

Description

Improper handling of highly compressed data in Amazon ion-java before 1.12.1 might allow remote attackers to cause a denial of service via a crafted compressed Ion document that expands to an arbitrarily large size upon decompression due to insufficient coverage of the GZIP auto-decompression opt-out introduced for CVE-2026-75936. To remediate this issue, users should upgrade to version 1.12.1.

SeverityHigh

CVSS7.5

Exploit probability—

ProductAmazon Ion-java

PublishedSep 4, 2026

First seenSep 4, 2026

Weakness typeCWE-409CWE-409

How to fix

Update

Amazon ion-java1.12.1 or later

Patches

github.com/amazon-ion/ion-java/releases/tag/v1.12.1

Vendor advisories

aws.amazon.com/security/security-bulletins/2026-100-aws/

Affected products

Product	Affected versions	Fixed in
Amazon ion-java	v < 1.12.1	1.12.1

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