Mattermost Desktop App versions <=5.13.3 fail to attach listeners restricting navigation to external sites within the Mattermost app which allows a malicious server to expose preload script functionality to untrusted servers via having a user open an external link in their Mattermost server. Mattermost Advisory ID: MMSA-2026-00596
CVE-2026-1628
MEDIUMPre-NVD 4.64.6—Trending — 4 sources updated this week
EchelonGraph scoreMEDIUM confidence
Score 4.6 from GitHub Security Advisory published 2026-03-02. a secondary CVSS source baseline 4.6; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: ghsa, secondary
4.6EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.6Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 4.6
- EG Score
- 4.6(medium)
- EG Risk
- 25(Track)EG Risk 25/100SSVC: 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 computedSeverity46% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 3%
- KEV
- Not listed
Published
March 2, 2026
Last Modified
June 17, 2026
References (1)
- responsibledisclosure@mattermosthttps://mattermost.com/security-updates
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 4× in last 7d / 4× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-27 14:13 UTCEPSS rescore
- 2026-07-27 14:00 UTCEG score recompute
- 2026-07-27 13:59 UTCGHSA enrichment
- 2026-07-27 13:57 UTCOSV refresh
Frequently asked(5)
What is CVE-2026-1628?
CVE-2026-1628 is a medium vulnerability published on March 2, 2026. Mattermost Desktop App versions <=5.13.3 fail to attach listeners restricting navigation to external sites within the Mattermost app which allows a malicious server to expose preload script functionality to untrusted servers via having a user open an external link in their Mattermost server.…
When was CVE-2026-1628 disclosed?
CVE-2026-1628 was first published in the National Vulnerability Database on March 2, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-1628 actively exploited?
CVE-2026-1628 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 96.5% of all scored CVEs.
What is the CVSS score of CVE-2026-1628?
CVE-2026-1628 has a CVSS v3 base score of 4.6 (NVD).
How do I remediate CVE-2026-1628?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-1628, 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-2026-1628
Is Your Infrastructure Affected by CVE-2026-1628?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.