Team messaging and collaboration.
CVE-2026-101049 in Heym before 0.0.53 allows remote unauthenticated attackers to forge Slack webhook events by bypassing signature verification when trigger nodes lack credential IDs or have empty signing secrets. Attackers can invoke workflows with the webhook owner's credentials without authentication. The vulnerability has a CVSS score of 6.5 and affects any Slack workspace using vulnerable Heym versions.
The 'Salesbleed' attack method exploits Salesforce AI agents to inject malicious instructions into Slack messages, enabling phishing attacks through trusted internal communication channels. By manipulating agentic AI, attackers can smuggle arbitrary instructions across integrated applications to reach Slack users within organizations.
CVE-2026-61699 is a high-severity vulnerability (CVSS 8.1) in nebula-mesh, Slack's self-hosted mesh VPN control plane. Prior to version 0.7.1, the blocklist mechanism fails to reach peer configurations, allowing attackers who exfiltrate host credentials to maintain full network overlay access for 30–365 days after revocation. Operator-visible state (UI and audit logs) does not accurately reflect the compromised host's actual connectivity status. Update to version 0.7.1 or later to remediate.
Security researchers at Zenity Labs demonstrated an indirect prompt-injection attack chain in Claude in Chrome that enables account takeovers of Slack and other services. The exploit tricks the AI agent into executing arbitrary code within authenticated browser sessions, allowing attackers to intercept email-based verification codes used for Slack account authentication. The vulnerability chain involves malicious email content, package registry manipulation, and automated credential theft.
Slack OAuth tokens were harvested during a Klue platform breach on June 11, 2026. Attackers who compromised Klue's backend injected malicious code that stole OAuth credentials from customers using Klue to integrate with Slack, Salesforce, and other enterprise tools. The extortion-focused threat group Icarus is attributed to the attack. Affected Slack organizations should revoke compromised OAuth tokens and review integration access logs.