Weakness (CWE)
CWE-158: Improper Neutralization of Null Byte or NUL Character
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes NUL characters or null bytes when they are sent to a downstream component.
How to prevent it (3 mitigations)
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Developers should anticipate that null characters or null bytes will be injected/removed/manipulated 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.
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Implementation
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.
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Implementation
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.
Source: MITRE CWE-158
11 results · Clear filters · Feed
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High 8.7
Improper neutralization of a NUL byte in cPanel allows remote attackers to read any mail account's calendar and contact…
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High 7.6
OpenVPN 2.7_alpha1 through 2.7.7 allows remote authenticated users to impersonate others via a crafted certificate subj…
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High 7.8
Aegisub executes arbitrary code through automatically loaded Automation scripts
Aegisub is a cross-platform advanced subtitle editor. From 3.2.0 to 3.4.2, Aegisub automatically loads Automation scripts referenced by `Automation Scripts` metadata in `ASS` subtitle projects without asking whether the user trusts the scripts or their author…
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High 8.1
Path Traversal through Search Head Clustering in Splunk Enterprise
In Splunk Enterprise versions below 10.4.2, 10.2.6, 10.0.9, and 9.4.14, a user who does not hold the "admin" or "power" Splunk roles could affect system integrity and availability by sending a crafted Representational State Transfer (REST) API request that de…
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High 8.7
free5GC UDM vulnerable to null byte injection in URL path parameters causing 500 Internal Server Error
Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. Versions prior to 1.4.2 are vulnerable to null byte injection in URL path parameters. A remote attacker can inject null bytes (URL-encoded as %00) into the supi p…
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High 8.9
Unauthenticated Arbitrary File Read via Null Byte Injection
Unauthenticated Arbitrary File Read via Null Byte Injection in DB Electronica Telecomunicazioni S.p.A. Mozart FM Transmitter versions 30, 50, 100, 300, 500, 1000, 2000, 3000, 3500, 6000, 7000 allows an attacker to perform Null byte injection in download_setti…
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High 8.7
Denial of Service in CivetWeb
A vulnerability in the CivetWeb library's function mg_handle_form_request allows remote attackers to trigger a denial of service (DoS) condition. By sending a specially crafted HTTP POST request containing a null byte in the payload, the server enters an infi…
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High 7.3
Adding %00 and a fake extension to a jar: URL changed the interpretation of the contents
jar: URLs retrieve local file content packaged in a ZIP archive. The null and everything after it was ignored when retrieving the content from the archive, but the fake extension after the null was used to determine the type of content. This could have been u…
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High 8.8
Red Lion Crimson Improper Neutralization of Null Byte or NUL Character
The Crimson 3.2 Windows-based configuration tool allows users with administrative access to define new passwords for users and to download the resulting security configuration to a device. If such a password contains the percent (%) character, invalid values …
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High 8.6
Select Dell Client Consumer and Commercial platforms include an issue that allows the BIOS Admin password to be changed…
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High 8.8
Unspecified vulnerability in the QuickTime Movie Parser Filter in quartz.dll in DirectShow in Microsoft DirectX 7.0 thr…
KEV May 20, 2026