Exim 4 before 4.94.2 has Improper Initialization that can lead to recursion-based stack consumption or other consequences. This occurs because use of certain getc functions is mishandled when a client uses BDAT instead of DATA.
Weakness
The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Exim | Exim | 4.88 (including) | 4.94.2 (excluding) |
| Exim4 | Ubuntu | bionic | * |
| Exim4 | Ubuntu | devel | * |
| Exim4 | Ubuntu | esm-infra/bionic | * |
| Exim4 | Ubuntu | esm-infra/focal | * |
| Exim4 | Ubuntu | focal | * |
| Exim4 | Ubuntu | groovy | * |
| Exim4 | Ubuntu | hirsute | * |
| Exim4 | Ubuntu | impish | * |
| Exim4 | Ubuntu | jammy | * |
| Exim4 | Ubuntu | trusty | * |
| Exim4 | Ubuntu | xenial | * |
Potential Mitigations
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable’s type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.