How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.
CVSS metrics in full
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector: Network — reachable from anywhere that can route to the service.
- Attack complexity: Low — the attack works reliably, with no preparation.
- Privileges required: None — an unauthenticated stranger can try it.
- User interaction: None — nobody has to be tricked into anything.
- Scope: Unchanged — the damage stays inside the vulnerable component.
- Confidentiality impact: None.
- Integrity impact: None.
- Availability impact: High — total loss, or loss the attacker controls.
Weakness class
CVE-2026-5740 is classified as CWE-789: Memory Allocation with Excessive Size Value. The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
Affected software
CVE-2026-5740 is recorded against 5 packages.
- github.com/mattermost/mattermost-server
- github.com/mattermost/mattermost-server/v5
- github.com/mattermost/mattermost-server/v6
- github.com/mattermost/mattermost/server/v8
- mattermost-server (from 11.6.0 up to 11.6.1)
Timeline and source
Published on 26 May 2026 and last revised on 7 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.
References
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Package)
mattermost.com (Web)
Other advisories for this package
github.com/mattermost/mattermost-server has other advisories on record. If you are patching this one, these are worth checking on the same host:
Same weakness in other software
These advisories are the same class of weakness (CWE-789: Memory Allocation with Excessive Size Value) in other software:
