AWS patches Babelfish flaw reachable before login on the SQL Server port

AWS patches Babelfish flaw reachable before login on the SQL Server port

6 November 2026: AWS has fixed CVE-2026-119923, a memory-safety flaw in how Babelfish for PostgreSQL handles the TDS connection handshake, which a remote attacker with no credentials could use against the confidentiality, integrity and availability of the database process. A second flaw needs a login. Aurora PostgreSQL customers with Babelfish enabled should apply pending maintenance.

Not yet independently verified. AWS publishes no CVSS score and makes no statement on exploitation in these bulletins. We list the main fixed releases, and the full set of intermediate ones is on the AWS page. We will update this when it can be confirmed, and remove this note.

What the two flaws do

Babelfish lets PostgreSQL answer SQL Server's TDS protocol, so applications written for SQL Server can talk to Aurora with few changes. Both flaws sit in that translation layer.

CVE-2026-119923 is in connection handshake handling and is the one to worry about, because the handshake comes before any authentication. CVE-2026-119924 is in remote procedure call handling and needs an authenticated actor, who could read adjacent process memory or cause a denial of service.

AWS rates the bulletin "Important (requires attention)". It gives no CVSS score and does not say whether either flaw has been exploited.

Versions by product

For the open source extension, the affected lines are 1.0 to 1.5, 2.1 to 2.15, 3.1 to 3.12, 4.0 to 4.8 and 5.1 to 5.4, and the fixes are 4.10, 5.6 and 6.1. Teams on the 1.x, 2.x or 3.x extension lines have no fix named in their own line and will have a larger move to plan.

For Aurora PostgreSQL, the main fixed releases, with their Babelfish versions, are:

• 13.9.16 (1.5.5) and 13.23.3 (1.17.2)
• 14.6.16 (2.3.5) and 14.23.1 (2.17.0)
• 15.18.1 (3.14.0)
• 16.14.1 (4.10.0)
• 17.10.1 (5.6.0)
• 18.3.4 (6.0.2) and 18.4.1 (6.1.0)

The bulletin lists further intermediate patch releases, so a cluster on an older minor version should be checked against the full table.

Closing port 1433 until maintenance runs

Pending maintenance on Aurora can sit waiting for a window that was set long ago, so teams should check whether the update has actually run instead of assuming it has. Until it does, AWS gives one workaround: limit the TDS port, 1433 by default, to trusted sources with VPC security groups.

A group that opened 1433 widely during a move off SQL Server and never closed it is the case to look for. Any cluster with Babelfish on but no remaining TDS clients could reasonably have the port closed for good.

A separate notice on an example script

AWS also published bulletin 2026-173 the same day. CVE-2026-122193 is an OS command injection in an example script from the Trusted Remote Execution set-up guide, which creates the SSM documents Rex-RO and Rex-RW. The script was not a shipped artefact and AWS has removed it, and anyone who created those documents from it should delete them.

Sources

• AWS security bulletin 2026-166: Babelfish for Aurora PostgreSQL, 6 November 2026, 6 November 2026
• AWS security bulletin 2026-173: Trusted Remote Execution example script, 6 November 2026, 6 November 2026