Mattermost versions 11.6.x <= 11.6.5, 10.11.x <= 10.11.20, 11.8.x <= 11.8.1, 11.7.x <= 11.7.4 fail to limit the number of frames and enforce the file size cap on animated GIF uploads, which allows an authenticated attacker to cause a denial of service via a crafted animated GIF uploaded as a custom emoji.. Mattermost Advisory ID: MMSA-2026-00695
{
"unresolved_ranges": [
{
"extracted_events": [
{
"introduced": "11.6.0"
},
{
"last_affected": "11.6.5"
},
{
"introduced": "10.11.0"
},
{
"last_affected": "10.11.20"
},
{
"introduced": "11.8.0"
},
{
"last_affected": "11.8.1"
},
{
"introduced": "11.7.0"
},
{
"last_affected": "11.7.4"
}
],
"source": "AFFECTED_FIELD"
}
],
"cwe_ids": [
"CWE-409"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/10xxx/CVE-2026-10819.json",
"cna_assigner": "Mattermost"
}{
"source": "CPE_RANGE",
"extracted_events": [
{
"introduced": "10.11.0"
},
{
"fixed": "10.11.21"
},
{
"introduced": "11.6.0"
},
{
"fixed": "11.6.6"
},
{
"introduced": "11.7.0"
},
{
"fixed": "11.7.5"
},
{
"introduced": "11.8.0"
},
{
"fixed": "11.8.2"
}
],
"cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*"
}