Mattermost Desktop App crashes when malformed arguments are provided to some exposed IPC methods
Mattermost Desktop App versions <=6.2 6.0.2 5.6.13.0 fail to validate payloads sent from the Mattermost Web App to the Desktop App which allows a malicious server owner to crash the Mattermost Desktop App via changing the payload of a method to a malformed one. Mattermost Advisory ID: MMSA-2026-00678
- Published
- Jul 17, 2026
- Updated
- Jul 30, 2026
- EPSS
- 0.4% · 34th percentile
- CWE
- CWE-400
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Report tools
Action score
26
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · Mattermost
- 5.7
- NVD has not scored this yet; the score shown is the CNA’s.
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 |
|---|---|---|
| mattermost | mattermost desktop | cpe:2.3:a:mattermost:mattermost_desktop |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- mattermost mattermost desktop5.6.13 and later · before 5.13.7
- mattermost mattermost desktop6.0.2 and later · before 6.2.1
- mattermost mattermost desktopafter 6.2.1 · before 6.3
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Mattermost). Independent of NVD's CPE analysis and usually ahead of it.
Mattermost Mattermost
- 6.3.0, 6.2.1.0, 5.13.7.0not affected
- up to and including 6.0.2affected · semver
- up to and including 5.6.13affected · semver
Same product
mattermost: all recordsOther highest-scoring records for the same primary product.
- CVE-2016-11064An issue was discovered in Mattermost Desktop App before 3.4.0.39Monitor
- CVE-2019-20856An issue was discovered in Mattermost Desktop App before 4.3.0 on macOS.39Monitor
- CVE-2019-20861An issue was discovered in Mattermost Desktop App before 4.2.2.35Monitor
- CVE-2024-39613RCE in desktop app in Windows by local attacker31Monitor
- CVE-2026-6517Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed30Monitor
- CVE-2020-14456An issue was discovered in Mattermost Desktop App before 4.4.0.29Monitor
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.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- game0v3rfinder
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- A low-privileged account is enough.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-400 · Uncontrolled Resource ConsumptionCVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvd-secondary
Root cause
Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.
The bug in code
The whole CWE-400 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
function expand(node) { return node.children.map(expand);}Fixed
const MAX_DEPTH = 32;function expand(node, depth = 0) { if (depth > MAX_DEPTH) throw new Error("too deep"); return node.children.map((c) => expand(c, depth + 1));}Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.