Weakness (CWE)
CWE-172: Improper Encoding or Decoding of Data
The product does not properly encode or decode data, resulting in unexpected values that are not equivalent to the original data.
How to prevent it (3 mitigations)
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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
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).
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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-172
20 results · Feed
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Medium 6.3
ModSecurity: HTML decoder missing entities, leading to evasion
ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 2.9.15 and 3.0.17, t:htmlEntityDecode recognizes only a small subset of named HTML entities, so rules that depend on the transformation can…
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Medium 6.1
fast-uri vulnerable to URI scheme spoofing via percent-encoded scheme decoding
fast-uri is a dependency-free RFC 3986 URI parser and serializer for Node.js. In versions before 2.4.8, from 3.0.0 through 3.1.8, and from 4.0.0 through 4.2.2, fast-uri percent-decodes the scheme component with the legacy global unescape() function before val…
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Medium 5.3
NGINX ngx_http_v3_module vulnerability
Description NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_v3_module module. When using HTTP/3 with proxy_request_buffering on directive, an unauthenticated attacker may be able to inject data in the proxied request. Impact This vulnera…
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Medium 5.8
OWASP Coraza WAF: jsDecode Off-by-One in Octal Escape Handling Enables WAF Bypass
OWASP Coraza WAF is a golang modsecurity compatible web application firewall library. From 3.0.0 until 3.8.0, the t:jsDecode transformation in internal/transformations/js_decode.go:64-70 includes the backslash in the octal buffer, causing ParseInt to fail and…
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Medium 6.0
RabbitMQ: Malformed UTF-8 in shortstr properties permanently disables RPC consumers
The RabbitMQ Java client library allows Java and JVM-based applications to connect to and interact with RabbitMQ nodes. Prior to 5.36.0, ValueReader.readShortstr decodes malformed UTF-8 bytes into replacement characters that can re-encode beyond the AMQP shor…
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High 7.3
Trusted Domain Project OpenDMARC Internationalized Domain Name opendmarc_policy.c opendmarc_policy_query_dmarc encoding error
A vulnerability has been found in Trusted Domain Project OpenDMARC up to 1.4.2. Affected by this issue is the function opendmarc_policy_query_dmarc in the library libopendmarc/opendmarc_policy.c of the component Internationalized Domain Name Handler. Such man…
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Medium 4.8
fast-uri vulnerable to mailto header injection via percent-encoded field-name desynchronization
fast-uri is a dependency-free RFC 3986 URI parser for Node.js, used by Fastify and ajv, that added a mailto scheme parser in version 4.1.3. In versions 4.1.3 and 4.1.4, the mailto parser compares each query field name to the reserved names to, subject, and bo…
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Medium 5.1
Symfony: UrlGenerator Dot-Segment Encoding Skips Every Other Chained `../` or `./` → Generated URL Collapses Off-Route Under RFC 3986 Normalization
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. Prior to 5.4.53, 6.4.41, 7.4.13, and 8.0.13, UrlGenerator::doGenerate() used strtr() dot-segment encoding that skipped every other chained ../ or ./ segment, all…
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Medium 5.8CVE-2026-42926 Public exploit
NGINX ngx_http_proxy_v2_module vulnerability
When NGINX Open Source is configured to proxy HTTP/2 traffic by setting proxy_http_version to 2, and also uses proxy_set_body, an attacker may be able to inject frame headers and payload bytes to the upstream peer. Note: Software versions which have reached …
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High 7.5CVE-2025-12758 Public exploit
Validator is Vulnerable to Incomplete Filtering of One or More Instances of Special Elements
Versions of the package validator before 13.15.22 are vulnerable to Incomplete Filtering of One or More Instances of Special Elements in the isLength() function that does not take into account Unicode variation selectors (\uFE0F, \uFE0E) appearing in a sequen…
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High 7.9
Libmodsecurity3 has possible bypass of encoded HTML entities
Libmodsecurity is one component of the ModSecurity v3 project. The library codebase serves as an interface to ModSecurity Connectors taking in web traffic and applying traditional ModSecurity processing. A bug that exists only in Libmodsecurity3 version 3.0.1…
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Low 2.0
SpiceDB calls to LookupResources using LookupResources2 with caveats may return context is missing when it is not
SpiceDB is an open source database for scalably storing and querying fine-grained authorization data. Starting in version 1.35.0 and prior to version 1.37.1, clients that have enabled `LookupResources2` and have caveats in the evaluation path for their reques…
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Low —
The kstring integration in gix-attributes is unsound
`gix-attributes` (in [`state::ValueRef`](https://github.com/Byron/gitoxide/blob/gix-attributes-v0.22.2/gix-attributes/src/state.rs#L19-L27)) unsafely creates a `&str` from a `&[u8]` containing non-UTF8 data, with the justification that so long as nothing read…
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Low 2.5
Reflected cross-site scripting in development mode handler in Vaadin
URL encoding error in development mode handler in `com.vaadin:flow-server` versions 2.0.0 through 2.6.1 (Vaadin 14.0.0 through 14.6.1), 3.0.0 through 6.0.9 (Vaadin 15.0.0 through 19.0.8) allows local user to execute arbitrary JavaScript code by opening crafte…
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Low 2.5
Reflected cross-site scripting in development mode handler in Vaadin 14, 15-19
URL encoding error in development mode handler in com.vaadin:flow-server versions 2.0.0 through 2.6.1 (Vaadin 14.0.0 through 14.6.1), 3.0.0 through 6.0.9 (Vaadin 15.0.0 through 19.0.8) allows local user to execute arbitrary JavaScript code by opening crafted …
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High 7.5
Update unsound DrainFilter and RString::retain
An issue was discovered in the abi_stable crate before 0.9.1 for Rust. DrainFilter lacks soundness because of a double drop.
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High 7.7
Cisco Adaptive Security Appliance Software SSL VPN Denial of Service Vulnerability
A vulnerability in the Secure Sockets Layer (SSL) VPN feature of Cisco Adaptive Security Appliance (ASA) Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition that prevents the creation of new SSL/Transport Layer …
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Medium 5.0
A flaw was discovered in fence-agents, prior to version 4.3.4, where using non-ASCII characters in a guest VM's comment…
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Critical 9.8
A security regression of CVE-2019-9636 was discovered in python since commit d537ab0ff9767ef024f26246899728f0116b1ec3 a…
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Critical 9.8
restforce vulnerable to Improper Input Validation
Insufficient URI encoding in restforce before 3.0.0 allows attacker to inject arbitrary parameters into Salesforce API requests.