Lack of URL normalization allows rendering previews for disallowed domains
Mattermost fails to normalize UTF confusable characters when determining if a preview should be generated for a hyperlink, allowing an attacker to trigger link preview on a disallowed domain using a specially crafted link.
- Published
- May 29, 2023
- Updated
- Jun 17, 2026
- EPSS
- 0.4% · 33th percentile
- CWE
- CWE-20
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Report tools
Action score
21
Monitor
Low priority for now.
- CVSS
- 21 / 40 · 5.3 / 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
- 5.3
- CNA · Mattermost
- 4.3
- 1.0 point gap
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| mattermost | mattermost | cpe:2.3:a:mattermost:mattermost |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- mattermost mattermost5.34.0 and later · before 7.1.9
- mattermost mattermost7.2.0 and later · before 7.8.4
- mattermost mattermost7.9.0 and later · before 7.9.3
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
- 7.1.9, 7.8.4, 7.9.3, 7.10not affected
- before 7.1.9affected · semver
- before 7.8.4affected · semver
- before 7.9.3affected · semver
Same product
mattermost: all recordsOther highest-scoring records for the same primary product.
- CVE-2024-39777Malicious remote can invite itself to an arbitrary local channel38Monitor
- CVE-2023-2193Oauth authorization codes do not expire when deauthorizing an oauth2 app36Monitor
- CVE-2019-20851An issue was discovered in Mattermost Mobile Apps before 1.26.0.36Monitor
- CVE-2024-40886One-click Client-Side Path Traversal Leading to CSRF in User Management admin page35Monitor
- CVE-2023-7114Mattermost version 2.10.0 and earlier fails to sanitize deeplink paths, which allows an attacker to perform CSRF attacks against the server.35Monitor
- CVE-2024-39832Permanently local data deletion by malicious remote34Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Mattermost Mattermost | 7.1.9 | Vendor (CNA) |
| Mattermost Mattermost | 7.8.4 | Vendor (CNA) |
| Mattermost Mattermost | 7.9.3 | Vendor (CNA) |
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.
- xpxfinder
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.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- low · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-20 · Improper Input ValidationCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
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)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Object Relational Mapping InjectionCAPEC-109likelihood: Low · High
- SQL Injection through SOAP Parameter TamperingCAPEC-110likelihood: High · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
ATT&CK techniques
- Obfuscated Files or InformationT1027
- Masquerading: Invalid Code SignatureT1036.001
- Steal Web Session CookieT1539
- Subvert Trust Controls: Code SigningT1553.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; 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 helpChange log
- Fix✗ → ✓
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References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.