High 7.5Published Oct 1, 2026

CVE-2026-104020Uncontrolled recursion in the Ion reader in Amazon Ion Python

Updated under an hour ago (2026-10-19 06:30 UTC)

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It affects Amazon ion-python. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.44%, higher than 37% of scored CVEs.

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Every CVE for Amazon ion-python

Exploited in the last 30 days

Uncontrolled recursion in the Ion reader in Amazon Ion Python before 0.15.0 might allow a remote unauthenticated actor to crash the application using the library, resulting in a denial of service, via a crafted, deeply nested Ion value. To remediate this issue, users should upgrade to version 0.15.0 or later.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-674
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.44% (percentile 37)
Assigned by: AMZN
NVD analysis: Deferred
Record last updated: Oct 9, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Amazon ion-python amazon:ion_python (from the name)	before 0.15.0	CNA record

References

https://github.com/amazon-ion/ion-python/releases/tag/v0.15.0patch
https://aws.amazon.com/security/security-bulletins/2026-122-aws/vendor-advisory
https://github.com/amazon-ion/ion-python/security/advisories/GHSA-93q6-f8hx-vv7fthird-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.