Deadlock Affecting runfinch-finch package, versions <0:1.19.0-1.amzn2023.0.1


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.5% (41st percentile)

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  • Snyk IDSNYK-AMZN2023-RUNFINCHFINCH-20250186
  • published29 Sept 2026
  • disclosed2 Sept 2026

Introduced: 2 Sep 2026

NewCVE-2026-56855  (opens in a new tab)
CWE-833  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 runfinch-finch to version 0:1.19.0-1.amzn2023.0.1 or higher.
This issue was patched in ALAS2023-2026-3140.

NVD Description

Note: Versions mentioned in the description apply only to the upstream runfinch-finch package and not the runfinch-finch package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking.

CVSS Base Scores

version 3.1