Is CVE-2026-101099 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-101099 being exploited in the wild.

How severe is CVE-2026-101099?

Medium severity, with a CVSS score of 4.3, published 28 September 2026.

Which products and versions are affected?

Ag-Ui-Protocol ag-ui Kotlin SDK up to 2026-09-23.

Is there a fix for CVE-2026-101099?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-101099 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-101099?

Check whether you run Ag-Ui-Protocol ag-ui Kotlin SDK at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-101099: ag-ui Kotlin SDK exception handling flaw in SseParser

CVE-2026-101099 · Severity: medium · CVSS 4.3 · Published 2026-09-28

The ag-ui Kotlin SDK is vulnerable to improper exception handling when parsing JSON events from agent endpoints. A deeply nested JSON payload can trigger a StackOverflowError that bypasses the parser's exception handler, causing the application or Android process to terminate unexpectedly, disrupting service availability.

Vendors: Ag-Ui-Protocol.

Quick answers

Is CVE-2026-101099 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-101099 being exploited in the wild.
How severe is CVE-2026-101099?: Medium severity, with a CVSS score of 4.3, published 28 September 2026.
Which products and versions are affected?: Ag-Ui-Protocol ag-ui Kotlin SDK up to 2026-09-23.
Is there a fix for CVE-2026-101099?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-101099 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-101099?: Check whether you run Ag-Ui-Protocol ag-ui Kotlin SDK at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The SseParser.kt component in ag-ui's Kotlin Community SDK uses kotlinx.serialization without a parse-depth limit, allowing deeply nested JSON to trigger StackOverflowError (an Error, not Exception) that escapes the catch(Exception) handler. This is a CWE-755 (improper exception handling) and CWE-400 (uncontrolled resource consumption) issue; a remote attacker controlling a malicious or compromised agent endpoint can craft input to cause process termination. The fix awaits acceptance in a pending pull request.

Affected products

ag-ui-protocol ag-ui Kotlin SDK up to 2026-09-23

Timeline

2026-09-28: disclosed
other: Pull request to fix awaits acceptance

References

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