How severe is CVE-2025-62605?

CVE-2025-62605 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2025-62605 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-62605?

CVE-2025-62605 primarily affects Joinmastodon Mastodon. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-62605?

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

Does CVE-2025-62605 have an EU (EUVD) identifier?

Yes. CVE-2025-62605 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-35213.

When was CVE-2025-62605 published?

CVE-2025-62605 was published on 2025-10-21 and last updated on 2026-06-17.

CVE-2025-62605

CVE-2025-62605 is a medium-severity vulnerability in Joinmastodon Mastodon with a CVSS 3.x base score of 4.3. 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-754.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-35213
Weakness: CWE-754
Affected product: Joinmastodon Mastodon
Published: 2025-10-21
Last modified: 2026-06-17

Description

Mastodon is a free, open-source social network server based on ActivityPub. In Mastodon version 4.4, support for verifiable quote posts with quote controls was added, but it is possible for an attacker to bypass these controls in Mastodon versions prior to 4.4.8 and 4.5.0-beta.2. Mastodon internally treats reblogs as statuses. Since they were not special-treated, an attacker could reblog any post, then quote their reblog, technically quoting themselves, but having the quote feature a preview of the post they did not get authorization for with all of the affordances that would be otherwise denied by the quote controls. This issue has been patched in versions 4.4.8 and 4.5.0-beta.2.

Frequently asked questions

What is CVE-2025-62605?: Mastodon is a free, open-source social network server based on ActivityPub. In Mastodon version 4.4, support for verifiable quote posts with quote controls was added, but it is possible for an attacker to bypass these controls in Mastodon versions prior to 4.4.8 and 4.5.0-beta.2. Mastodon internally treats reblogs as statuses. Since they were not special-treated, an attacker could reblog any post, then quote their reblog, technically quoting themselves, but having the quote feature a preview of the post they did not get authorization for with all of the affordances that would be otherwise denied by the quote controls. This issue has been patched in versions 4.4.8 and 4.5.0-beta.2.
How severe is CVE-2025-62605?: CVE-2025-62605 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2025-62605 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-62605?: CVE-2025-62605 primarily affects Joinmastodon Mastodon. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-62605?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-62605 have an EU (EUVD) identifier?: Yes. CVE-2025-62605 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-35213.
When was CVE-2025-62605 published?: CVE-2025-62605 was published on 2025-10-21 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
cpe:2.3:a:joinmastodon:mastodon:4.5.0:beta1:*:*:*:*:*:*

More vulnerabilities in Joinmastodon Mastodon

CVE-2023-36460 — Critical (CVSS 9.9): Mastodon is a free, open-source social network server based on ActivityPub. Starting in version 3.5.0 and prior to…
CVE-2022-2166 — Critical (CVSS 9.8): Improper Restriction of Excessive Authentication Attempts in GitHub repository mastodon/mastodon prior to 4.0.0.
CVE-2022-24307 — Critical (CVSS 9.8): Mastodon before 3.3.2 and 3.4.x before 3.4.6 has incorrect access control because it does not compact incoming signed…
CVE-2018-21018 — Critical (CVSS 9.8): Mastodon before 2.6.3 mishandles timeouts of incompletely established sessions.
CVE-2024-23832 — Critical (CVSS 9.4): Mastodon is a free, open-source social network server based on ActivityPub Mastodon allows configuration of LDAP for…
CVE-2023-36459 — Critical (CVSS 9.3): Mastodon is a free, open-source social network server based on ActivityPub. Starting in version 1.3 and prior to…

All CVEs affecting Joinmastodon Mastodon →

Other CWE-754 (Improper Check for Unusual or Exceptional Conditions) vulnerabilities

CVE-2026-24054 — Critical (CVSS 10.0): Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs)…
CVE-2021-0211 — Critical (CVSS 10.0): An improper check for unusual or exceptional conditions in Juniper Networks Junos OS and Junos OS Evolved Routing…
CVE-2026-8091 — Critical (CVSS 9.8): Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150,…
CVE-2024-52316 — Critical (CVSS 9.8): Unchecked Error Condition vulnerability in Apache Tomcat. If Tomcat is configured to use a custom Jakarta…
CVE-2024-7826 — Critical (CVSS 9.8): Improper Check for Unusual or Exceptional Conditions vulnerability in Webroot SecureAnywhere - Web Shield on Windows,…
CVE-2023-37303 — Critical (CVSS 9.8): An issue was discovered in the CheckUser extension for MediaWiki through 1.39.3. In certain situations, an attempt to…

Browse all CWE-754 (Improper Check for Unusual or Exceptional Conditions) vulnerabilities →