What is CVE-2023-49952?

CVE-2023-49952 is a high-severity vulnerability in Joinmastodon Mastodon, classified under Cross-site Scripting. CVSS score: 7.5/10. Published 2024-11-18.

How severe is CVE-2023-49952?

High severity. CVSS v3 base score is 7.5 out of 10.

XSS in Joinmastodon Mastodon

CVE-2023-49952

Mastodon 4.1.x before 4.1.17 and 4.2.x before 4.2.9 allows a bypass of rate limiting via a crafted HTTP request header.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2024-11-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.005 (39.3th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Joinmastodon Mastodon

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/mastodon/mastodon/security (Product)
github.com/mastodon/mastodon/security/advisories/GHSA-c2r5-cfqr-c553 (Vendor Advisory)

Frequently asked questions

What is CVE-2023-49952?: CVE-2023-49952 is a high-severity vulnerability in Joinmastodon Mastodon, classified under Cross-site Scripting. CVSS score: 7.5/10. Published 2024-11-18.
How severe is CVE-2023-49952?: High severity. CVSS v3 base score is 7.5 out of 10.