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Matrix Media RepoApplication · T2bot

CVE-2024-56515

MEDIUM · 6.5 CVSS v3.1 Published 2025-01-16
Fix available
A fix is available. Upgrade to 1.3.8 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Matrix Media Repo (MMR) is a highly configurable multi-homeserver media repository for Matrix. If SVG or JPEGXL thumbnailers are enabled (they are disabled by default), a user may upload a file which claims to be either of these types and request a thumbnail to invoke a different decoder in ImageMagick. In some ImageMagick installations, this includes the capability to run Ghostscript to decode the image/file. If MP4 thumbnailers are enabled (also disabled by default), the same issue as above may occur with the ffmpeg installation instead. MMR uses a number of other decoders for all other file types when preparing thumbnails. Theoretical issues are possible with these decoders, however in testing they were not possible to exploit. This is fixed in MMR v1.3.8. MMR now inspects the mimetype of media prior to thumbnailing, and picks a thumbnailer based on those results instead of relying on user-supplied values. This may lead to fewer thumbnails when obscure file shapes are used. This also helps narrow scope of theoretical issues with all decoders MMR uses for thumbnails. Users are advised to upgrade. Users unable to upgrade may disable the SVG, JPEGXL, and MP4 thumbnail types in the MMR config which prevents the decoders from being invoked. Further disabling uncommon file types on the server is recommended to limit risk surface. Containers and other similar technologies may also be used to limit the impact of vulnerabilities in external decoders, like ImageMagick and ffmpeg. Some installations of ImageMagick may disable "unsafe" file types, like PDFs, already. This option can be replicated to other environments as needed. ffmpeg may be compiled with limited decoders/codecs. The Docker image for MMR disables PDFs and similar formats by default.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Matrix Media Repo trusts user-supplied MIME types when generating thumbnails. An attacker can upload a file claiming to be SVG, JPEGXL, or MP4 format and request thumbnail generation, causing ImageMagick or ffmpeg to invoke a different decoder (including Ghostscript in some ImageMagick installations). This type confusion allows potential code execution through vulnerable external decoders. Version 1.3.8 fixes this by inspecting actual file MIME types before thumbnailing instead of relying on user-supplied values.

MitigationUpgrade to MMR v1.3.8 or higher, which validates actual MIME types before selecting thumbnailers. If upgrading is not possible, disable SVG, JPEGXL, and MP4 thumbnail types in the MMR configuration, and consider using containers to isolate thumbnail processing.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Matrix Media RepoApplication
Affected:< 1.3.8

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Matrix Media Repo installation
    Check for MMR service/process running on the system. Look for MMR configuration files typically located in /etc/mmr or similar config directories, or check for Docker container named 'matrix-media-repo'.
    Affected if Matrix Media Repo is installed and running in the environment
  2. Determine MMR version
    Check the installed MMR version by running 'matrix-media-repo --version' if CLI is available, or inspect the container image tag/Dockerfile, or check the binary/file version metadata.
    Affected if The installed version is below 1.3.8 (e.g., 1.3.7, 1.3.6, etc.)
  3. Check thumbnail configuration for SVG
    Inspect MMR configuration file (typically config.yaml) for thumbnail settings. Look for 'svg' under thumbnailing, mimes, or similar configuration sections. Check if SVG thumbnail generation is explicitly enabled or present in the allowed types.
    Affected if SVG thumbnail generation is enabled in MMR config
  4. Check thumbnail configuration for JPEGXL
    Inspect MMR configuration file for 'jxl', 'jpegxl', or 'image/jxl' entries in thumbnail-related settings. Verify if JPEGXL format is permitted for thumbnail generation.
    Affected if JPEGXL thumbnail generation is enabled in MMR config
  5. Check thumbnail configuration for MP4
    Inspect MMR configuration file for 'mp4', 'video/mp4', or 'video' entries in thumbnail or preview settings. Verify if MP4 video thumbnail generation is permitted.
    Affected if MP4 thumbnail generation is enabled in MMR config
  6. Verify external decoder availability
    Check if ImageMagick (convert/identify commands), ffmpeg, or Ghostscript are installed on the same system or available to the MMR container. These are the external decoders that can be exploited via type confusion.
    Affected if ImageMagick, ffmpeg, or Ghostscript are installed and accessible to MMR for thumbnail processing

Environment is affected if Matrix Media Repo version is below 1.3.8 AND any of SVG, JPEGXL, or MP4 thumbnail generation is enabled, especially when external decoders like ImageMagick or ffmpeg are available to process the files.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.3.8 or later
Fixed in 1.3.8
Interim mitigation

Upgrade to MMR v1.3.8 or higher, which validates actual MIME types before selecting thumbnailers. If upgrading is not possible, disable SVG, JPEGXL, and MP4 thumbnail types in the MMR configuration, and consider using containers to isolate thumbnail processing.

Recommended fix High confidence

v1.3.8 or later

  1. 1. Upgrade Matrix Media Repo to version 1.3.8 or later
  2. 2. After upgrading, verify that MMR now inspects the mimetype of media prior to thumbnailing rather than relying on user-supplied values
  3. 3. If unable to upgrade, disable SVG, JPEGXL, and MP4 thumbnail types in the MMR configuration file
  4. 4. Consider disabling other uncommon file types on the server to limit attack surface
  5. 5. If using containers, ensure proper isolation is in place to limit impact of decoder vulnerabilities
Caveat May produce fewer thumbnails when obscure file shapes are used due to stricter mimetype validation

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Matrix Media Repo Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-56515 in production — separate from our analysis above.

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What this is

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