CVE-2023-2808
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
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.
- Record
CVE-2023-2808- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-20
- Updated
- 2026-11-02
EUVDEUVD-2023-34261
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.
- Record
EUVD-2023-34261- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-vc9q-cghx-53cj
Mattermost fails to normalize UTF confusable characters when determining if a preview should be...
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.
- Record
GHSA-vc9q-cghx-53cj- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-20
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2023-2808- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N - CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-20
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2023-2808- CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-20
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-2808 is a medium vulnerability (CVSS 4.3) in Mattermost, published May 29, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.41%, the 35th percentile. No source names a fixed version.