--- id: "CVE-2026-24423" kind: "vulnerability" aliases: ["CVE-2026-24423"] title: "SmarterTools SmarterMail versions prior to build 9511 contain an unauthenticated remote code execution vulnerability\u2026" severity: "critical" cvss: 9.8 epss: null exploited: true status: "open" category: "other" products: [{"name": "smartertools smartermail", "fixed": ["100.0.9511"], "affected": "< 100.0.9511", "ecosystem": "vendor"}, {"name": "SmarterTools SmarterMail", "fixed": [], "affected": "", "ecosystem": "vendor"}] ecosystems: ["vendor"] tags: ["cloudflare", "exploited", "lab-disclosure", "other", "ransomware", "self-hosted", "smartermail", "windows"] not_affected_if: ["managed-hosting", "unknown"] published_at: "2026-01-23T17:16:13+00:00" first_seen_at: "2026-10-23T19:11:51+00:00" updated_at: "2026-10-24T18:56:54+00:00" sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-24423", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24423", "first_seen_at": "2026-10-23T23:44:51+00:00"}, {"source": "lab", "url": "https://developers.cloudflare.com/changelog/post/2026-05-04-waf-release/", "first_seen_at": "2026-10-24T18:56:54+00:00"}] --- # SmarterTools SmarterMail versions prior to build 9511 contain an unauthenticated remote code execution vulnerability… SmarterTools SmarterMail has a missing authentication flaw in its ConnectToHub API method, which lets an unauthenticated caller point the mail server at a malicious HTTP server. That server can then serve an OS command that SmarterMail executes, giving the attacker command execution on the mail host. _Summary, check and fix written by a model from the sources; labelled as such._ ## Affected - vendor:smartertools smartermail affected < 100.0.9511 fixed 100.0.9511 - vendor:SmarterTools SmarterMail affected ? fixed ? ## Fix Apply the mitigation from the SmarterTools vendor instructions, or discontinue use of SmarterMail if no mitigation is available (per CISA KEV required action). Follow BOD 22-01 guidance if the instance is a cloud service. ## Mitigated for you by - Cloudflare (waf-rule, since 2026-05-04): covers HTTP requests proxied through Cloudflare, detected by the Cloudflare Managed Ruleset rule 'SmarterMail - Remote Code Execution - CVE:CVE-2026-24423', changed from Log to Block Limits: none stated Still: monitor the Security Events dashboard and adjust rule actions as needed https://developers.cloudflare.com/changelog/post/2026-05-04-waf-release/ ## Timeline - 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-24423 - 2026-10-23T23:44:51+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-24423 - 2026-10-24T18:56:54+00:00 lab https://developers.cloudflare.com/changelog/post/2026-05-04-waf-release/ — Cloudflare: WAF Release - 2026-05-04 · Changelog ## Documents - [advisory] Cloudflare: WAF Release - 2026-05-04 · Changelog https://developers.cloudflare.com/changelog/post/2026-05-04-waf-release/ ## From the sources WAF Release - 2026-05-04 · Changelog # Changelog New updates and improvements at Cloudflare. May 4, 2026 ## WAF Release - 2026-05-04 This week's release focuses on new detections to expand coverage across command injection, SQL injection, PHP object injection, remote code execution, and XSS attack vectors. Key Findings - Existing rule enhancements have been deployed to improve detection resilience against broad classes of web attacks and strengthen behavioral coverage. Continuous Rule Improvements We are continuously refining our managed rules to provide more resilient protection and deeper insights into attack patterns. To ensure an optimal security posture, we recommend consistently monitoring the Security Events dashboard and adjusting rule actions as these enhancements are deployed. | Ruleset | Rule ID | Legacy Rule ID | Description | Previous Action | New Action | Comments | | --- | --- | --- | --- | --- | --- | --- | | Cloudflare Managed Ruleset | ...f0884a68 | N/A | XSS, HTML Injection - Object Tag - Body (beta) | Log | Block | This is a new detection. This rule is merged into the original rule "XSS, HTML Injection - Object Tag" (ID: ...0c14e284). | | Cloudflare Managed Ruleset | ...ff012303 | N/A | XSS, HTML Injection - Object Tag - Headers | Log | Block | This is a new detection. The rule previously known as "XSS, HTML Injection - Object Tag - Headers (beta)" is now renamed to "XSS, HTML Injection - Object Tag - Headers". | | Cloudflare Managed Ruleset | ...16f921d9 | N/A | XSS, HTML Injection - Object Tag - URI | Log | Block | This is a new detection. The rule previously known as "XSS, HTML Injection - Object Tag - URI (beta)" is now renamed to "XSS, HTML Injection - Object Tag - URI". | | Cloudflare Managed Ruleset | ...dc90d21a | N/A | Command Injection - Generic 9 - Body Vector - Beta | N/A | Disabled | This is a new detection. This rule is merged into the original rule "Command Injection - Generic 9 - Body Vector" (ID: ...0677175f) | | Cloudflare Managed Ruleset | ...f8960375 | N/A | Command Injection - Generic 9 - Header Vector - Beta | N/A | Disabled | This is a new detection. This rule is merged into the original rule "Command Injection - Generic 9 - Header Vector" (ID: ...1eb7a999) | | Cloudflare Managed Ruleset | ...ef47a800 | N/A | Command Injection - Generic 9 - URI Vector - Beta | N/A | Disabled | This is a new detection. This rule is merged into the original rule "Command Injection - Generic 9 - URI Vector" (ID: ...97321c6c) | | Cloudflare Managed Ruleset | ...beebf804 | N/A | Command Injection - Sleep - Body | N/A | Disabled | This is a new detection. The rule previously known as "Command Injection Sleep" is now renamed to "Command Injection - Sleep - Body". | | Cloudflare Managed Ruleset | ...0d257566 | N/A | Command Injection - Sleep - Headers | N/A | Disabled | This is a new detection. | | Cloudflare Managed Ruleset | ...1856fe86 | N/A | Command Injection - Sleep - URI | N/A | Disabled | This is a new detection. | | Cloudflare Managed Ruleset | ...e6e43c37 | N/A | Fortinet FortiSandbox - Command Injection - CVE:CVE-2026-39808 | Log | Block | This is a new detection. | | Cloudflare Managed Ruleset | ...88118795 | N/A | Remote Code Execution - Common Bash Bypass - Headers | N/A | Disabled | This is a new detection. | | Cloudflare Managed Ruleset | ...9299d53b | N/A | Remote Code Execution - Common Bash Bypass - URI | N/A | Disabled | This is a new detection. | | Cloudflare Managed Ruleset | ...b0bf33f9 | N/A | Remote Code Execution - Common Bash Bypass - Body - Beta | N/A | Disabled | This is a new detection. This rule is merged into the original rule "Remote Code Execution - Common Bash Bypass Body" (ID: ...efb7e5b9). The rule previously known as "Remote Code Execution - Common Bash Bypass Beta" is now renamed to "Remote Code Execution - Common Bash Bypass Body". | | Cloudflare Managed Ruleset | ...33bfe8b9 | N/A | PHP Object Injection - 2 - Body - Beta | N/A | Disabled | This is a new detection. This rule is merged into the original rule "PHP Object Injection - 2" (ID: ...161aafdc) | | Cloudflare Managed Ruleset | ...29552387 | N/A | PHP Object Injection - 2 - Headers | N/A | Disabled | This is a new detection. | | Cloudflare Managed Ruleset | ...8104f4c5 | N/A | PHP Object Injection - 2 - URI | N/A | Disabled | This is a new detection. | | Cloudflare Managed Ruleset | ...6a46201e | N/A | SQLi - DROP - 2 - Beta | N/A | Disabled | This is a new detection. This rule is merged into the original rule "SQLi - DROP - 2" (ID: ...48ac2221) | | Cloudflare Managed Ruleset | ...8b7f85ee | N/A | SQLi - DROP - 2 - Headers | N/A | Disabled | This is a new detection. | | Cloudflare Managed Ruleset | ...1546b5f0 | N/A | SQLi - DROP - 2 - URI | N/A | Disabled | This is a new detection. | | Cloudflare Managed Ruleset | ...1e053dce | N/A | SmarterMail - Remote Code Execution - CVE:CVE-2026-24423 | Log | Block | This is a new detection. | | Cloudflare Managed Ruleset | ...d0023a36 | N/A | SQLi - SELECT Expression - Body | Block | Disabled | Action changed | | Cloudflare Managed Ruleset | ...26cc211f | N/A | SQLi - String Concatenation - URI | Block | Disabled | Action changed | --- _Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_