CVE-2022-41040

CVE-2022-41040 is a server-side request forgery (SSRF, CWE-918) vulnerability in Microsoft Exchange Server, publicly tracked under the name "ProxyNotShell" together with CVE-2022-41082. It is triggered when an attacker sends crafted HTTP requests to exposed Exchange web endpoints (such as Autodiscover), causing the server to issue attacker-influenced requests to itself. On its own the SSRF coerces authenticated server-side requests, but when chained with the CVE-2022-41082 remote code execution flaw it gives the attacker code execution on the Exchange server, typically followed by web shells, data access, and — in observed campaigns — ransomware deployment. Organizations running on-premises Microsoft Exchange Server are affected; the source data lists only Microsoft Exchange Server and does not specify affected version ranges, and hosted Exchange Online is a separate product not listed here. The vulnerability is being actively exploited in the wild: it was added to CISA's Known Exploited Vulnerabilities catalog on 2022-09-30 with known ransomware use, and EPSS assigns it a 100% probability of exploitation within 30 days; no public PoC is listed.

What to do: Apply Microsoft's Exchange Server security updates per vendor instructions immediately, as required by the CISA KEV catalog. As interim mitigation, restrict or block untrusted internet access to Exchange web endpoints (e.g., Autodiscover, OWA, ECP), and review IIS logs for suspicious crafted requests indicating SSRF or the chained CVE-2022-41082 exploitation. Given documented ransomware use, prioritize any internet-facing Exchange server and hunt for web shells and post-exploitation activity.