Signal is active with 2 mentions in latest observed window
Recommended action window: Monitor and triage in normal cycle
NVD description
Mattermost versions 11.5.x <= 11.5.1, 11.4.x <= 11.4.3 fail to validate the X-Requested-With header on the burn-on-read reveal endpoint which allows an authenticated channel member to force the reveal of a burn-on-read message without recipient consent via a crafted Markdown image tag.. Mattermost Advisory ID: MMSA-2026-00636
Priority
LOW
Exploitation
NONE
PoC
NONE
Patch
NONE
Momentum
NONE
If you run products in this scope, you should treat this CVE as relevant to your environment.
⚡ New CVE Alert: CVE-2026-6339 📊 Severity: 4.3 🚨 Risk Level: Medium 🧩 Affects: Multiple / Unspecified Products Reference: https://nvd.nist.gov/vuln/detail/CVE-2026-6339 #CVE-2026-6339 #CVE #Medium #CyberSecurity #InfoSec https://t.co/iWh71IaLOj
Post summary
A new CVE (CVE-2026-6339) is announced with medium severity, but no further technical or mitigation details are provided.
CVE-2026-6339 Burn-On-Read Message Reveal Vulnerability in Mattermost 11... https://vulmon.com/vulnerabilitydetails?qid=CVE-2026-6339 Don't wait vulnerability scanning results: https://alerts.vulmon.com/?utm_source=twitter&utm_medium=social&utm_campaign=2102281&utm_content=2
Post summary
This tweet announces the discovery of CVE‑2026‑6339, a Burn‑On‑Read Message Reveal vulnerability in Mattermost 11, and directs readers to a Vulmon vulnerability details page for more information.
1 of 1 entries
| Part | Vendor | Product | Version | Target SW | Target HW |
|---|---|---|---|---|---|
| App | mattermost | mattermost_server | - | - | - |