CVE-2023-40703

Denial of Service via specially crafted block fields in Mattermost Boards

HIGH
7.5
CVSS Score
Published: November 27, 2023 at 09:08 AM UTC
Updated: June 17, 2026 at 06:19 AM UTC
1 product affected across 1 vendorMattermost

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Severity
HIGH7.5
Exploit prediction
EPSS 0.7%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ 7.8.12v ≤ 8.1.3v ≤ 9.0.1v ≤ 9.1.08.0.0 ≤ v ≤ 8.1.39.0.0 ≤ v ≤ 9.0.19.1.0
Vendor states this is fixed in 7.8.13 (unaffected)
Vendor states this is fixed in 8.1.4 (unaffected)
Vendor states this is fixed in 9.0.2 (unaffected)
Vendor states this is fixed in 9.1.1 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-400

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