CVE-2023-42452

Mastodon vulnerable to Stored XSS through the translation feature

MEDIUM
5.4
CVSS Score
Published: September 19, 2023 at 03:58 PM UTC
Updated: June 17, 2026 at 06:23 AM UTC
2 products affected across 2 vendorsMastodonMastodon

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Severity
MEDIUM5.4
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

Mastodon is a free, open-source social network server based on ActivityPub. In versions on the 4.x branch prior to versions 4.0.10, 4.2.8, and 4.2.0-rc2, under certain conditions, attackers can abuse the translation feature to bypass the server-side HTML sanitization, allowing unescaped HTML to execute in the browser. The impact is limited thanks to Mastodon's strict Content Security Policy, blocking inline scripts, etc. However a CSP bypass or loophole could be exploited to execute malicious XSS. Furthermore, it requires user interaction, as this can only occur upon clicking the “Translate” button on a malicious post. Versions 4.0.10, 4.2.8, 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.

4.0.0 ≤ v < 4.0.104.1.0 ≤ v < 4.1.84.2.0 beta14.2.0 beta24.2.0 beta34.2.0 rc1
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
v < 4.0.10v < 4.1.8v < 4.2.0-rc2
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:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

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

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-79

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