CWE-167
Improper Handling of Additional Special Element
The product receives input from an upstream component, but it does not handle or incorrectly handles when an additional unexpected special element is provided.
CVE-2025-25006 (GCVE-0-2025-25006)
Vulnerability from cvelistv5
Published
2025-08-12 17:09
Modified
2025-09-09 23:47
Severity ?
VLAI Severity ?
EPSS score ?
CWE
- CWE-167 - Improper Handling of Additional Special Element
Summary
Improper handling of additional special element in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
References
| ▼ | URL | Tags |
|---|---|---|
| https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-25006 | vendor-advisory |
Impacted products
| Vendor | Product | Version | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ▼ | Microsoft | Microsoft Exchange Server 2019 Cumulative Update 15 |
Version: 15.02.0 < 15.02.1748.036 |
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Mitigation
Phases:
Description:
- Developers should anticipate that extra special elements will be injected in the input vectors of their product. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
Mitigation ID: MIT-5
Phase: Implementation
Strategy: Input Validation
Description:
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Mitigation ID: MIT-28
Phase: Implementation
Strategy: Output Encoding
Description:
- While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).
Mitigation ID: MIT-20
Phase: Implementation
Strategy: Input Validation
Description:
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
No CAPEC attack patterns related to this CWE.