CVE-2026-94056
Description
A flaw was found in Exim. When the Proxy-Protocol is used with an attacker-controlled proxy, an attacker can read certain uninitialized data from stack memory. This information disclosure could potentially expose sensitive data.
Statement
Red Hat Product Security has determined that this vulnerability does not affect any currently supported Red Hat product. This assessment may evolve based on further analysis and discovery. For more information about this vulnerability and the products it affects, please see the linked references.
Mitigation
To prevent information disclosure, ensure that Exim is not configured to use the Proxy-Protocol with untrusted or potentially malicious upstream proxies. If the Proxy-Protocol feature is not essential for your deployment, disable it within the Exim configuration. Consult the official Exim documentation for instructions on how to modify or disable Proxy-Protocol settings. Any changes to the Exim configuration will require a service reload or restart to take effect, which may temporarily disrupt mail processing.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
If the uninitialized pointer is used in a read operation, an attacker might be able to read sensitive portions of memory.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the uninitialized pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the uninitialized pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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