CVE-2021-29453: matrix-media-repo is an open-source multi-domain media repository for Matrix

Q: How do I fix CVE-2021-29453?

matrix-media-repo: upgrade to 1.2.7. Exact commands for each OS are on this page.

Q: Is CVE-2021-29453 being exploited?

CVE-2021-29453 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-29453 affect?

CVE-2021-29453 affects matrix-media-repo. Severity is medium (CVSS 5.7). 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 mal

Q: How urgent is CVE-2021-29453?

Priority 36/100. No elevated risk signals yet.

Routine

MEDIUM 5.7UPGRADE

CVE-2021-29453 is a medium-severity flaw (CVSS 5.7) affecting matrix-media-repo. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 ex

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.7 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Weakness	CWE-400, CWE-770
Published	2021-04-19
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: matrix-media-repo project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-04-19 19:15 UTCPublished CVE record published
2026-06-17 03:47 UTCUpdated Record last modified

matrix-media-repo project matrix-media-repo UPGRADE

Affected: < 1.2.7

Fixed in: 1.2.7

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy matrix-media-repo || rpm -q matrix-media-repo || matrix-media-repo --version

2. UPGRADE to 1.2.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade matrix-media-repo

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade matrix-media-repo

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-29453?

matrix-media-repo: upgrade to 1.2.7. Exact commands for each OS are on this page.

Is CVE-2021-29453 being exploited?

CVE-2021-29453 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-29453 affect?

CVE-2021-29453 affects matrix-media-repo. Severity is medium (CVSS 5.7). 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 mal

How urgent is CVE-2021-29453?

Priority 36/100. No elevated risk signals yet.

Related CVEs

CVE-2024-56515 MEDIUM 6.8 UPGRADE Matrix Media Repo (MMR) is a highly configurable multi-homeserver media repository for Matrix
CVE-2024-52791 MEDIUM 5.3 UPGRADE Matrix Media Repo (MMR) is a highly configurable multi-homeserver media repository for Matrix
CVE-2024-52602 MEDIUM 5.0 UPGRADE Matrix Media Repo (MMR) is a highly configurable multi-homeserver media repository for Matrix
CVE-2024-36403 MEDIUM 5.3 UPGRADE Matrix Media Repo (MMR) is a highly configurable multi-homeserver media repository for Matrix
CVE-2024-36402 MEDIUM 5.3 UPGRADE Matrix Media Repo (MMR) is a highly configurable multi-homeserver media repository for Matrix

References

← Back to latest CVEs