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CRITICAL severity

CVE-2021-45693 — Messagepack-Rs

CRITICAL

CVE-2021-45693 is a critical-severity (CVSS 9.8) CWE-908 vulnerability in messagepack-rs_project messagepack-rs. A fix is available — see the affected versions and patch details below.

An issue was discovered in the messagepack-rs crate through 2021-01-26 for Rust. deserialize_string_primitive may read from uninitialized memory locations.

Published
Updated
Affected
1 product
Patched
See advisory
Exploits
None indexed
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs69th percentile — riskier than 69% of all scored CVEsHighest risk
0.00%0.58%1.15%1.73%0.4%1.2%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Description

An issue was discovered in the messagepack-rs crate through 2021-01-26 for Rust. deserialize_string_primitive may read from uninitialized memory locations.

Affected Products

1 product · 1 configurations
Application
messagepack-rsmessagepack-rs_project
< 0.8.1
range

Detection & mitigation playbook

Vendor / appliance
  1. Detect

    Inventory every messagepack-rs_project messagepack-rs deployment and check each version against the affected-products list above.

  2. Fix

    Apply the messagepack-rs_project messagepack-rs security patch or hotfix for CVE-2021-45693 on the affected version, following the vendor advisory for your exact build.

  3. Workarounds

    Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Frequently Asked Questions

An issue was discovered in the messagepack-rs crate through 2021-01-26 for Rust. deserialize_string_primitive may read from uninitialized memory locations.
O3 Security · Runtime Protection

Is CVE-2021-45693 being exploited in your environment?

Detect and block the exploit chain at execution, on systems you cannot patch yet.

CVE-2021-45693: Messagepack-Rs (Critical 9.8)