Use After Free in Linuxfoundation Tremor
CVE-2021-39228
Tremor is an event processing system for unstructured data. A vulnerability exists between versions 0.7.2 and 0.11.6. 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. The issue has been patched in version 0.11.6 by removing the optimization and always cloning the target expression of a Merge or Patch. If an upgrade is not possible, a possible workaround is to avoid the optimization by introducing a temporary variable and not immediately reassigning to `state`.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.013 (70.6th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 70.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000
Affected products
- Linuxfoundation Tremor
- Tremor-Rs Tremor-Runtime — versions > 0.7.2, < 0.11.6
Weakness classification (CWE)
References
- github.com/tremor-rs/tremor-runtime/security/advisories/GHSA-mc22-5q92-8v85 (Third Party Advisory, Mitigation)
- github.com/tremor-rs/tremor-runtime/pull/1217 (Exploit, Patch, Third Party Advisory)
- github.com/tremor-rs/tremor-runtime/commit/1a2efcdbe68e5e7fd0a05836ac32d2cde78a… (Patch, Third Party Advisory)
- github.com/tremor-rs/tremor-runtime/releases/tag/v0.11.6 (Third Party Advisory, Release Notes)
Frequently asked questions
- What is CVE-2021-39228?
- CVE-2021-39228 is a medium-severity vulnerability in Linuxfoundation Tremor, classified under Use After Free. CVSS score: 6.5/10. Published 2021-09-17.
- How severe is CVE-2021-39228?
- Medium severity. CVSS v3 base score is 6.5 out of 10.