Mastodon Remote user impersonation and takeover
Mastodon is a free, open-source social network server based on ActivityPub Mastodon allows configuration of LDAP for authentication. Due to insufficient origin validation in all Mastodon, attackers can impersonate and take over any remote account. Every Mastodon version prior to 3.5.17 is vulnerable, as well as 4.0.x versions prior to 4.0.13, 4.1.x version prior to 4.1.13, and 4.2.x versions prior to 4.2.5.
- Published
- Feb 1, 2024
- Updated
- Jun 17, 2026
- EPSS
- 2.5% · 84th percentile
- CWE
- CWE-290
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Report tools
Action score
40
Plan
Add it to your regular patch cycle.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.5%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 9.8
- CNA · GitHub_M
- 9.4
- 0.4 point gap
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| joinmastodon | mastodon | cpe:2.3:a:joinmastodon:mastodon |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- joinmastodon mastodonbefore 3.5.17
- joinmastodon mastodon4.0.0 and later · before 4.0.13
- joinmastodon mastodon4.1.0 and later · before 4.1.13
- joinmastodon mastodon4.2.0 and later · before 4.2.5
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
mastodon mastodon
- < 3.5.17, >= 4.0.0, < 4.0.13, >= 4.1.0, < 4.1.13, >= 4.2.0, < 4.2.5affected
Same product
joinmastodon: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-36460Mastodon vulnerable to arbitrary file creation through media attachments51Plan
- CVE-2018-21018Mastodon before 2.6.3 mishandles timeouts of incompletely established sessions.40Plan
- CVE-2022-2166Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon39Monitor
- CVE-2022-24307Mastodon before 3.3.2 and 3.4.x before 3.4.6 has incorrect access control because it does not compact incoming signed JSON-LD activities.39Monitor
- CVE-2026-41259Mastodon: Insufficient verification of email addresses32Monitor
- CVE-2024-37903Mastodon has improper authorship check on audience extension for existing posts32Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
—
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
- CVE-2024-2562318 days apartLack of media type verification of Activity Streams objects allows impersonation of remote accounts30Monitor
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-290 · Authentication Bypass by SpoofingCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Exploitation of Trusted IdentifiersCAPEC-21likelihood: High · High
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- Creating a Rogue Certification Authority CertificateCAPEC-459likelihood: Medium · Very High
- Web Services API Signature Forgery Leveraging Hash Function Extension WeaknessCAPEC-461High
- Signature SpoofCAPEC-473
- Signature Spoofing by MisrepresentationCAPEC-476likelihood: Low · High
- Session Credential Falsification through PredictionCAPEC-59likelihood: High · High
- Reusing Session IDs (aka Session Replay)CAPEC-60likelihood: High · High
ATT&CK techniques
- Masquerading: Invalid Code SignatureT1036.001
- Access Token ManipulationT1134
- Access Token Manipulation:Token Impersonation/TheftT1134.001
- Steal Application Access TokenT1528
- Steal Web Session CookieT1539
- Use Alternate Authentication Material:Web Session CookieT1550.004
- Subvert Trust Controls: Code SigningT1553.002
- Adversary-in-the-MiddleT1557
Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- www.openwall.com/lists/oss-security/2024/02/02/4
- github.com/mastodon/mastodon/commit/1726085db5cd73dd30953da858f9887bcc90b958
- github.com/mastodon/mastodon/security/advisories/GHSA-3fjr-858r-92rw
Vendor advisories and official records. Exploit/PoC links are deliberately left out.