CVE-2023-40703
Denial of Service via specially crafted block fields in Mattermost Boards
- Published
- Updated
- Reserved
- Assigned by
- Mattermost
Description
Mattermost fails to properly limit the characters allowed in different fields of a block in Mattermost Boards allowing a attacker to consume excessive resources, possibly leading to Denial of Service, by patching the field of a block using a specially crafted string.
Timeline
ID reserved
By Mattermost
- 5 days later
· 5 days later
Published
- 18 months later
· 18 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| MattermostCNA (assigner) | 3.1 | Medium4.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L |
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.72% · top 46% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.3.
Weakness
Affected products
- affected ≤ 7.8.12
- affected ≤ 8.1.3
- affected ≤ 9.0.1
- affected ≤ 9.1.0
- unaffected 9.1.1
- unaffected 9.0.2
- unaffected 7.8.13
- unaffected 8.1.4
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Gogithub.com/mattermost/mattermost-server/v6GHSA-c37r-v8jx-7cv2 (opens in a new tab)
- Gogithub.com/mattermost/mattermost/server/v8GHSA-c37r-v8jx-7cv2 (opens in a new tab)
What to do
Solution: Update Mattermost Server to versions 9.1.1, 9.0.2, 7.8.13, 8.1.4 or higher.
References (1)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-c37r-v8jx-7cv2 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2023-40703)Record last updated .