Security readout for executives and security teams
Plain-English summary
CVE-2026-22246 is a Mastodon privacy flaw. A registered local user could view lists of followers and followed accounts lost by other local users after moderation-related severance events. The leak does not identify which account lost those relationships. Organizations running Mastodon should update because the issue exposes sensitive social-graph information.
Executive priority
Prioritize patching in the normal urgent maintenance cycle for Mastodon-hosting organizations. This is not a system takeover issue, but it can expose sensitive community relationship data and undermine user trust, especially around moderation events.
Technical view
Mastodon’s severed-relationship download feature failed to verify ownership before returning relationship lists. Network access and a local authenticated account are required. Impact is confidentiality only, with CVSS 3.1 score 6.5. Affected versions are before 4.3.17, 4.4.0-beta.1 through before 4.4.11, and 4.5.0-beta.1 through before 4.5.4.
Likely exposure
Exposure is limited to Mastodon servers running affected versions with local registered users. The vulnerable data relates to severance events created by moderation actions. Public unauthenticated exploitation is not indicated by the provided sources.
Exploitation context
The source bundle does not report active exploitation, and the CVE is not marked as CISA KEV. The issue requires a local Mastodon account, but the access complexity is low once authenticated. Risk is highest for instances where relationship privacy and moderation confidentiality are important.
Researcher notes
Classified as CWE-201 information exposure. The advisory states the leaked lists exclude the account name that lost relationships, which limits but does not remove privacy impact. No exploit code or active exploitation evidence is provided in the source bundle.
Mitigation direction
- Upgrade Mastodon to 4.3.17, 4.4.11, 4.5.4, or later supported releases.
- Review Mastodon’s GitHub security advisory for version-specific upgrade guidance.
- If immediate upgrade is impossible, consult vendor guidance for temporary controls.
- Consider notifying administrators handling moderation-sensitive communities.
Validation and detection
- Inventory all Mastodon instances and record running versions.
- Confirm no instance runs versions below 4.3.17, 4.4.11, or 4.5.4 as applicable.
- Verify the deployed build includes the referenced ownership-check fixes.
- Review access logs for unusual use of severed-relationship download functionality, if logged.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-201: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-22246 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N2.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/mastodon/mastodon/security/advisories/GHSA-ww85-x9cp-5v24CVE reference · x_refsource_CONFIRM
- https://github.com/mastodon/mastodon/commit/68e30985ca7afdb89af1b2e9dc962e1993dc8076CVE reference · x_refsource_MISC
- https://github.com/mastodon/mastodon/commit/b2bcd34486fd6681cc0f30028086ef0f47282adfCVE reference · x_refsource_MISC
- https://github.com/mastodon/mastodon/commit/c1fb6893c5175d74c074f6f786d504c8bc610d57CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Insertion of Sensitive Information Into Sent Data
Insertion of Sensitive Information Into Sent Data represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.