CVE-2026-17578: Kong Event Gateway Encryption Flaw

CVE-2026-17578 Overview

CVE-2026-17578 affects Kong Event Gateway versions 1.0.0 through 1.1.1 and version 1.2.0 when the AWS Identity and Access Management (IAM) encryption feature is enabled. The gateway does not enforce Advanced Encryption Standard-Galois/Counter Mode (AES-GCM) key rotation before reaching the National Institute of Standards and Technology (NIST) SP 800-38D recommended usage limit for random nonces. Producers sending sustained high message volumes without a gateway reboot can drive the probability of a nonce collision to a non-negligible level. An authorized consumer that observes a collision can recover portions of the plaintext from affected messages. This weakness maps to CWE-323: Reusing a Nonce, Key Pair in Encryption.

Critical Impact
An authorized consumer able to detect an AES-GCM nonce collision can recover parts of plaintext from encrypted messages traversing the affected Kong Event Gateway.

Affected Products

Kong Event Gateway 1.0.0 through 1.1.1
Kong Event Gateway 1.2.0
Deployments with the AWS IAM encryption feature enabled

Discovery Timeline

2026-08-05 - CVE-2026-17578 published to the National Vulnerability Database (NVD)
2026-08-05 - Last updated in NVD database

Technical Details for CVE-2026-17578

Vulnerability Analysis

Kong Event Gateway uses AES-GCM to encrypt messages when AWS IAM encryption is configured. AES-GCM security relies on the uniqueness of the nonce for each encryption operation performed under a given key. NIST SP 800-38D limits the number of invocations under one key to approximately 2^32 when nonces are generated randomly. The affected releases do not rotate keys before that ceiling. Key rotation only occurs at gateway restart, so long-running instances processing sustained high throughput accumulate encryption operations that push nonce collision probability into a practically exploitable range. When two ciphertexts share both key and nonce, the AES-GCM keystream reuse enables recovery of plaintext XOR relationships and compromises authenticity guarantees.

Root Cause

The root cause is missing enforcement of a key rotation policy aligned with NIST SP 800-38D. The gateway generates AES-GCM nonces at random but does not track invocation counts or trigger rekeying before the safe-usage boundary. Rotation is tied to process lifecycle rather than cryptographic thresholds.

Attack Vector

Exploitation requires an authorized consumer that can observe encrypted messages emitted by a producer sustaining a high message rate against a Kong Event Gateway instance that has not been restarted. The consumer monitors ciphertexts and initialization vectors, detects a repeated nonce under the same key, and derives plaintext relationships from the colliding ciphertext pair. No network-level code execution is required. The attack is passive from a network perspective and does not require elevated privileges beyond legitimate consumer access.

No public proof-of-concept code is available for this issue. See the Kong Changelog for vendor technical details.

Detection Methods for CVE-2026-17578

Indicators of Compromise

Kong Event Gateway instances with uptime long enough to exceed 2^32 AES-GCM encryption operations under one key while AWS IAM encryption is enabled.
Duplicate 96-bit initialization vectors observed across encrypted messages sharing the same key context.
Consumers repeatedly requesting historical message ranges in patterns consistent with ciphertext collection.

Detection Strategies

Inventory Kong Event Gateway deployments and identify versions 1.0.0 through 1.1.1 and 1.2.0 with AWS IAM encryption enabled.
Instrument telemetry to record per-key encryption invocation counts and alert when counts approach the NIST SP 800-38D threshold.
Review consumer access logs for accounts performing unusually broad or repetitive message reads that could support offline collision analysis.

Monitoring Recommendations

Track gateway process uptime and correlate with message throughput to estimate AES-GCM key usage.
Alert on gateway instances that have not been restarted within operational rotation windows while running affected versions.
Forward Kong Event Gateway logs to a centralized analytics platform to baseline consumer behavior and flag anomalies.

How to Mitigate CVE-2026-17578

Immediate Actions Required

Upgrade Kong Event Gateway to version 1.1.2 or 1.2.1, which enforce automatic key rotation before the NIST SP 800-38D usage limit.
Restart any running affected instance to force immediate key rotation until the upgrade is deployed.
Restrict consumer permissions so only trusted identities can subscribe to sensitive topics protected by AWS IAM encryption.

Patch Information

Kong released fixed versions 1.1.2 and 1.2.1 of Event Gateway. These builds enforce automatic AES-GCM key rotation before the recommended usage boundary is reached. Full release notes are available in the Kong Changelog.

Workarounds

Schedule frequent restarts of Kong Event Gateway instances to force key rotation while an upgrade is pending.
Cap producer throughput or shard producers across multiple gateway instances to keep per-key encryption counts well below the NIST limit.
Reduce the retention window for encrypted messages to limit the ciphertext corpus available to any single consumer.

bash

# Configuration example
# Verify installed Kong Event Gateway version and plan upgrade to a fixed release
kong-event-gateway --version

# Upgrade to a patched release (1.1.2 or 1.2.1) per Kong deployment method
# Example placeholder for container-based deployments:
# docker pull kong/event-gateway:1.2.1
# docker stop <container> && docker run kong/event-gateway:1.2.1