Memory Safety Issue when using patch or merge on state and assign the result back to state

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

• CVE-2021-39228: 1.35% estimated exploitation activity in the next 30 days; percentile 71.52 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact This vulnerability is a memory safety Issue when using patch or merge on state and assign the result back to state. In this case affected versions of Tremor and the tremor-script crate maintains references to memory that might have been freed already. And these memory regions can be accessed by retrieving the state, e.g. send it over TCP or HTTP. This requires the Tremor server (or any other program using tremor-script) to execute a tremor-script script that uses the mentioned language construct. Details If affects the following two tremor-script language constructs: A Merge where we assign the result back to the target expression and the expression to be merged needs to reference the event: A Patch where we assign the result back to the target expression and the patch operations used need to reference the event: For constructs like this (it does not matter what it references in the expression to be merged or the patch operations) an optimization was applied to manipulate the…

Published by the source

20 Sep 2021, 19:52 UTC

Last modified by the source

30 Mar 2023, 23:45 UTC

Source last checked

26 Oct 2026, 15:33 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-mc22-5q92-8v85

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# Patch Next advisory brief: CVE-2021-39228

Advisory: Memory Safety Issue when using patch or merge on state and assign the result back to state
IDs: CVE-2021-39228, GHSA-mc22-5q92-8v85
Record: https://patchnext.com/advisories/cve-2021-39228 (revision 1, source checked 26 Oct 2026, 15:33 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tremor-script 0.11.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io tremor-script: affected >= 0.7.3, < 0.11.6; fixed in 0.11.6

## Suggested inspection (read-only)
- crates.io tremor-script: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on tremor-script.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-mc22-5q92-8v85 (GitHub-reviewed advisory GHSA-mc22-5q92-8v85 lists affected ranges: crates.io tremor-script >=0.7.3 <0.11.6)

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