CVE-2023-42451

Mastodon Invalid Domain Name Normalization vulnerability

HIGH

7.5

CVSS Score

Published: September 19, 2023 at 03:56 PM UTC

Updated: June 17, 2026 at 06:23 AM UTC

2 products affected across 2 vendorsMastodonMastodon

Using mastodon by mastodon?

Get instant alerts when new vulnerabilities affect mastodon - before attackers find them.

Real-time alertsTrack your software stackFree plan available

Start Free Sign In

Severity

HIGH7.5

Exploit prediction

EPSS 0.7%

SSVC

No known exploit

Description

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 3.5.14, 4.0.10, 4.1.8, and 4.2.0-rc2, under certain circumstances, attackers can exploit a flaw in domain name normalization to spoof domains they do not own. Versions 3.5.14, 4.0.10, 4.1.8, and 4.2.0-rc2 contain a patch for this issue.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Mastodon · Joinmastodon

95%

v < 3.5.144.0.0 ≤ v < 4.0.104.1.0 ≤ v < 4.1.84.2.0 beta1 4.2.0 beta2 4.2.0 beta3 4.2.0 rc1

Affected range stops below 3.5.14, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.0.10, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.1.8, so it looks safe — our inference, not a vendor statement

Mastodon · Mastodon

60%

v < 3.5.14v < 4.0.10v < 4.1.8v < 4.2.0-rc2

Affected range stops below 3.5.14, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.0.10, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.1.8, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.2.0-rc2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

x_refsource_MISCPatch

Source: [email protected]

https://github.com/mastodon/mastodon/commit/eeab3560fc0516070b3fb97e089b15ecab1938c8

x_refsource_CONFIRMVendor Advisory

Source: [email protected]

https://github.com/mastodon/mastodon/security/advisories/GHSA-v3xf-c9qf-j667

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: HIGH
Availability: NONE

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-706

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create account Sign in

Free plan, no card