AWS SageMaker Distribution CVE-2026-104019: code execution in Unified Studio Spaces, end-of-support versions left unfixed

AWS SageMaker Distribution CVE-2026-104019: code execution in Unified Studio Spaces, end-of-support versions left unfixed

2 October 2026 — AWS published security bulletin 2026-125-AWS on 2 October 2026 for CVE-2026-104019 in SageMaker Distribution, the image that runs Spaces in Amazon SageMaker Unified Studio. AWS has deployed a fix for supported versions that applies when a Space restarts. Two ranges of older versions are end of support and will not be fixed.

Not yet independently verified. Only AWS's own bulletin has been read; no independent report had been found at 2026-10-04. We will update this when it can be confirmed, and remove this note.

What the flaw does

When a SageMaker Space starts, its start-up script validates the network against every SageMaker connection in the project. AWS says that, under certain conditions, connection details were not sanitised properly during this step, which could let arbitrary code run in the Space of another project member. In projects with Trusted Identity Propagation enabled, a user with project contributor permissions or higher could gain another member's temporary execution-role credentials and call downstream AWS services on that member's behalf.

Which versions

AWS lists:

• 2.8.x to 2.13.x: all affected, no fix (end of support)
• 2.14.x before 2.14.12: fixed in 2.14.12
• 3.3.x to 3.8.x: all affected, no fix (end of support)
• 3.9.x before 3.9.12: fixed in 3.9.12
• 4.0.x before 4.0.11, 4.1.x before 4.1.11, 4.2.x before 4.2.8, 4.3.x before 4.3.5, 4.4.x before 4.4.3: fixed in those releases
• 4.5.x, and anything before 2.8.0 or 3.3.0: not affected

AWS lists no workaround.

What to do

1. Restart every Space on a supported minor version. AWS says Spaces adopt the latest patch of their minor line on restart, so no version choice is needed.
2. Find any Space or custom image on 2.8 to 2.13 or 3.3 to 3.8 and move it to a supported line, preferably 4.5, because those versions will stay vulnerable.
3. In projects with Trusted Identity Propagation, review who holds contributor permissions and check CloudTrail for calls made with members' execution roles that they do not recognise.

Why it matters for buyers

Shared data and machine-learning workspaces put many users' credentials side by side, so a flaw that crosses from one member to another is a credential problem, not just a notebook problem. The end-of-support clause is the part to act on: teams that pinned older images for compatibility now carry an unfixable flaw until they upgrade.

Sources

• AWS Security Bulletin 2026-125-AWS: CVE-2026-104019 in SageMaker Distribution — 2 October 2026