# CVE-2021-29433: Sydent DoS (via resource exhaustion) due to improper input validation

Source: https://junglewise.ai/threats/cve-2021-29433-sydent-dos-via-resource-exhaustion-due-to-improper-input  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-04-15  
License: CC BY 4.0 with a link back

CVE-2021-29433 · Severity: low · CVSS 3.1 · Published 2021-04-15

### Impact Missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion. ### Patches Fixed by 3175fd3. ### Workarounds There are no known workarounds. ### References n/a ### For more information If you have any questions or comments about this advisory, email us at security@matrix.org.

Technologies: [matrix-sydent (PyPI)](https://junglewise.ai/threats/technologies/matrix-sydent). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2021-29433 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-29433 being exploited in the wild.

**How severe is CVE-2021-29433?** Low severity, with a CVSS score of 3.1, published 15 April 2021.

**Which products and versions are affected?** matrix-sydent (PyPI) ECOSYSTEM:introduced=0,fixed=2.3.0.

**Is there a fix for CVE-2021-29433?** Yes. matrix-sydent (PyPI): upgrade to 2.3.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2021-29433?** Check whether you run matrix-sydent (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- matrix-sydent (PyPI): upgrade to 2.3.0 or later

  ```sh
  pip install "matrix-sydent>=2.3.0"
  ```


## Affected products

- matrix-sydent (PyPI) ECOSYSTEM:introduced=0,fixed=2.3.0

## Identifiers

- CVE-2021-29433
- GHSA-pw4v-gr34-2553
- PYSEC-2021-24

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- [PYSEC-2026-843 - Matrix Sydent mishandles emails](https://junglewise.ai/threats/cve-2019-11340-matrix-sydent-mishandles-emails)
- [Sydent does not verify email server certificates](https://junglewise.ai/threats/cve-2023-38686-sydent-does-not-verify-email-server-certificates)
- [SSRF in Sydent due to missing validation of hostnames](https://junglewise.ai/threats/cve-2021-29431-ssrf-in-sydent-due-to-missing-validation-of-hostnames)
- [Malicious users could abuse Sydent to control the content of invitation emails](https://junglewise.ai/threats/cve-2021-29432-malicious-users-could-abuse-sydent-to-control-the-content-of)