How severe is CVE-2021-29453?

CVE-2021-29453 has a CVSS 3.x base score of 5.7, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-29453 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-29453?

CVE-2021-29453 affects Matrix-media-repo Project Matrix-media-repo. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-29453?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-29453 published?

CVE-2021-29453 was published on 2021-04-19 and last updated on 2026-06-17.

CVE-2021-29453

CVE-2021-29453 is a medium-severity vulnerability in Matrix-media-repo Project Matrix-media-repo with a CVSS 3.x base score of 5.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: Medium (CVSS 3.x base score 5.7)
CVSS v2: 4.0
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Matrix-media-repo Project Matrix-media-repo
Published: 2021-04-19
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-29453?: 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.
How severe is CVE-2021-29453?: CVE-2021-29453 has a CVSS 3.x base score of 5.7, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-29453 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-29453?: CVE-2021-29453 affects Matrix-media-repo Project Matrix-media-repo. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-29453?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-29453 published?: CVE-2021-29453 was published on 2021-04-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:matrix-media-repo_project:matrix-media-repo:*:*:*:*:*:*:*:*

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