Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to sanitize team email addresses to be visible only to Team Admins, which allows any authenticated user to view team email addresses via the GET /api/v4/channels/{channel_id}/common_teams endpoint
CVE-2025-12559
MEDIUMNVD 4.34.3—
EchelonGraph scoreMEDIUM confidence
This medium-severity CVE scores 4.3 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 89% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, nvd
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 4.3
- EG Score
- 4.3(medium)
- EG Risk
- 19(Track)EG Risk 19/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity43% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 12%
- KEV
- Not listed
Published
November 27, 2025
Last Modified
December 3, 2025
References (1)
- responsibledisclosure@mattermosthttps://mattermost.com/security-updates
Related CVEs
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Frequently asked(5)
What is CVE-2025-12559?
CVE-2025-12559 is a medium vulnerability published on November 27, 2025. Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to sanitize team email addresses to be visible only to Team Admins, which allows any authenticated user to view team email addresses via the GET /api/v4/channels/{channelid}/commonteams endpoint
When was CVE-2025-12559 disclosed?
CVE-2025-12559 was first published in the National Vulnerability Database on November 27, 2025, with the most recent update on December 3, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-12559 actively exploited?
CVE-2025-12559 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 87.9% of all scored CVEs.
What is the CVSS score of CVE-2025-12559?
CVE-2025-12559 has a CVSS v3 base score of 4.3 (NVD).
How do I remediate CVE-2025-12559?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-12559, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2025-12559
Is Your Infrastructure Affected by CVE-2025-12559?
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