solidity/docs/bugs.json

[
    {
        "name": "ExpExponentCleanup",
        "summary": "Using the ** operator with an exponent of type shorter than 256 bits can result in unexpected values.",
        "description": "Higher order bits in the exponent are not properly cleaned before the EXP opcode is applied if the type of the exponent expression is smaller than 256 bits and not smaller than the type of the base. In that case, the result might be larger than expected if the exponent is assumed to lie within the value range of the type. Literal numbers as exponents are unaffected as are exponents or bases of type uint256.",
        "fixed": "0.4.25",
        "severity": "medium/high",
        "check": {"regex-source": "[^/]\\*\\* *[^/0-9 ]"}
    },
    {
        "name": "EventStructWrongData",
        "summary": "Using structs in events logged wrong data.",
        "description": "If a struct is used in an event, the address of the struct is logged instead of the actual data.",
        "introduced": "0.4.17",
        "fixed": "0.4.25",
        "severity": "very low",
        "check": {"ast-compact-json-path": "$..[?(@.nodeType === 'EventDefinition')]..[?(@.nodeType === 'UserDefinedTypeName' && @.typeDescriptions.typeString.startsWith('struct'))]"}
    },
    {
        "name": "PublicLibFunctionsDoNotReturnNestedArrays",
        "summary": "Calls to public library functions (internal functions are safe) that return nested arrays return only zeroes.",
        "description": "The compiler does not complain about public library functions (internal functions are safe) returning nested arrays, but it also does not return it correctly. Thus, the function caller receives only zeroes.",
        "introduced": "0.4.11",
        "fixed": "0.4.22",
        "severity": "low"
    },
    {
        "name": "OneOfTwoConstructorsSkipped",
        "summary": "If a contract has both a new-style constructor (using the constructor keyword) and an old-style constructor (a function with the same name as the contract) at the same time, one of them will be ignored.",
        "description": "If a contract has both a new-style constructor (using the constructor keyword) and an old-style constructor (a function with the same name as the contract) at the same time, one of them will be ignored. There will be a compiler warning about the old-style constructor, so contracts only using new-style constructors are fine.",
        "introduced": "0.4.22",
        "fixed": "0.4.23",
        "severity": "very low"
    },
	{
		"name": "NestedArrayFunctionCallDecoder",
		"summary": "Calling functions that return multi-dimensional fixed-size arrays can result in memory corruption.",
		"description": "If Solidity code calls a function that returns a multi-dimensional fixed-size array, array elements are incorrectly interpreted as memory pointers and thus can cause memory corruption if the return values are accessed. Calling functions with multi-dimensional fixed-size arrays is unaffected as is returning fixed-size arrays from function calls. The regular expression only checks if such functions are present, not if they are called, which is required for the contract to be affected.",
		"introduced": "0.1.4",
		"fixed": "0.4.22",
		"severity": "medium",
		"check": {"regex-source": "returns[^;{]*\\[\\s*[^\\] \\t\\r\\n\\v\\f][^\\]]*\\]\\s*\\[\\s*[^\\] \\t\\r\\n\\v\\f][^\\]]*\\][^{;]*[;{]"}
	},
    {
        "name": "ZeroFunctionSelector",
        "summary": "It is possible to craft the name of a function such that it is executed instead of the fallback function in very specific circumstances.",
        "description": "If a function has a selector consisting only of zeros, is payable and part of a contract that does not have a fallback function and at most five external functions in total, this function is called instead of the fallback function if Ether is sent to the contract without data.",
        "fixed": "0.4.18",
        "severity": "very low"
    },
    {
        "name": "DelegateCallReturnValue",
        "summary": "The low-level .delegatecall() does not return the execution outcome, but converts the value returned by the functioned called to a boolean instead.",
        "description": "The return value of the low-level .delegatecall() function is taken from a position in memory, where the call data or the return data resides. This value is interpreted as a boolean and put onto the stack. This means if the called function returns at least 32 zero bytes, .delegatecall() returns false even if the call was successuful.",
        "introduced": "0.3.0",
        "fixed": "0.4.15",
        "severity": "low"
    },
    {
        "name": "ECRecoverMalformedInput",
        "summary": "The ecrecover() builtin can return garbage for malformed input.",
        "description": "The ecrecover precompile does not properly signal failure for malformed input (especially in the 'v' argument) and thus the Solidity function can return data that was previously present in the return area in memory.",
        "fixed": "0.4.14",
        "severity": "medium"
    },
    {
        "name": "SkipEmptyStringLiteral",
        "summary": "If \"\" is used in a function call, the following function arguments will not be correctly passed to the function.",
        "description": "If the empty string literal \"\" is used as an argument in a function call, it is skipped by the encoder. This has the effect that the encoding of all arguments following this is shifted left by 32 bytes and thus the function call data is corrupted.",
        "fixed": "0.4.12",
        "severity": "low"
    },
    {
        "name": "ConstantOptimizerSubtraction",
        "summary": "In some situations, the optimizer replaces certain numbers in the code with routines that compute different numbers.",
        "description": "The optimizer tries to represent any number in the bytecode by routines that compute them with less gas. For some special numbers, an incorrect routine is generated. This could allow an attacker to e.g. trick victims about a specific amount of ether, or function calls to call different functions (or none at all).",
        "link": "https://blog.ethereum.org/2017/05/03/solidity-optimizer-bug/",
        "fixed": "0.4.11",
        "severity": "low",
        "conditions": {
            "optimizer": true
        }
    },
    {
        "name": "IdentityPrecompileReturnIgnored",
        "summary": "Failure of the identity precompile was ignored.",
        "description": "Calls to the identity contract, which is used for copying memory, ignored its return value. On the public chain, calls to the identity precompile can be made in a way that they never fail, but this might be different on private chains.",
        "severity": "low",
        "fixed": "0.4.7"
    },
    {
        "name": "OptimizerStateKnowledgeNotResetForJumpdest",
        "summary": "The optimizer did not properly reset its internal state at jump destinations, which could lead to data corruption.",
        "description": "The optimizer performs symbolic execution at certain stages. At jump destinations, multiple code paths join and thus it has to compute a common state from the incoming edges. Computing this common state was simplified to just use the empty state, but this implementation was not done properly. This bug can cause data corruption.",
        "severity": "medium",
        "introduced": "0.4.5",
        "fixed": "0.4.6",
        "conditions": {
            "optimizer": true
        }
    },
    {
        "name": "HighOrderByteCleanStorage",
        "summary": "For short types, the high order bytes were not cleaned properly and could overwrite existing data.",
        "description": "Types shorter than 32 bytes are packed together into the same 32 byte storage slot, but storage writes always write 32 bytes. For some types, the higher order bytes were not cleaned properly, which made it sometimes possible to overwrite a variable in storage when writing to another one.",
        "link": "https://blog.ethereum.org/2016/11/01/security-alert-solidity-variables-can-overwritten-storage/",
        "severity": "high",
        "introduced": "0.1.6",
        "fixed": "0.4.4"
    },
    {
        "name": "OptimizerStaleKnowledgeAboutSHA3",
        "summary": "The optimizer did not properly reset its knowledge about SHA3 operations resulting in some hashes (also used for storage variable positions) not being calculated correctly.",
        "description": "The optimizer performs symbolic execution in order to save re-evaluating expressions whose value is already known. This knowledge was not properly reset across control flow paths and thus the optimizer sometimes thought that the result of a SHA3 operation is already present on the stack. This could result in data corruption by accessing the wrong storage slot.",
        "severity": "medium",
        "fixed": "0.4.3",
        "conditions": {
            "optimizer": true
        }
    },
    {
        "name": "LibrariesNotCallableFromPayableFunctions",
        "summary": "Library functions threw an exception when called from a call that received Ether.",
        "description": "Library functions are protected against sending them Ether through a call. Since the DELEGATECALL opcode forwards the information about how much Ether was sent with a call, the library function incorrectly assumed that Ether was sent to the library and threw an exception.",
        "severity": "low",
        "introduced": "0.4.0",
        "fixed": "0.4.2"
    },
    {
        "name": "SendFailsForZeroEther",
        "summary": "The send function did not provide enough gas to the recipient if no Ether was sent with it.",
        "description": "The recipient of an Ether transfer automatically receives a certain amount of gas from the EVM to handle the transfer. In the case of a zero-transfer, this gas is not provided which causes the recipient to throw an exception.",
        "severity": "low",
        "fixed": "0.4.0"
    },
    {
        "name": "DynamicAllocationInfiniteLoop",
        "summary": "Dynamic allocation of an empty memory array caused an infinite loop and thus an exception.",
        "description": "Memory arrays can be created provided a length. If this length is zero, code was generated that did not terminate and thus consumed all gas.",
        "severity": "low",
        "fixed": "0.3.6"
    },
    {
        "name": "OptimizerClearStateOnCodePathJoin",
        "summary": "The optimizer did not properly reset its internal state at jump destinations, which could lead to data corruption.",
        "description": "The optimizer performs symbolic execution at certain stages. At jump destinations, multiple code paths join and thus it has to compute a common state from the incoming edges. Computing this common state was not done correctly. This bug can cause data corruption, but it is probably quite hard to use for targeted attacks.",
        "severity": "low",
        "fixed": "0.3.6",
        "conditions": {
            "optimizer": true
        }
    },
    {
        "name": "CleanBytesHigherOrderBits",
        "summary": "The higher order bits of short bytesNN types were not cleaned before comparison.",
        "description": "Two variables of type bytesNN were considered different if their higher order bits, which are not part of the actual value, were different. An attacker might use this to reach seemingly unreachable code paths by providing incorrectly formatted input data.",
        "severity": "medium/high",
        "fixed": "0.3.3"
    },
    {
        "name": "ArrayAccessCleanHigherOrderBits",
        "summary": "Access to array elements for arrays of types with less than 32 bytes did not correctly clean the higher order bits, causing corruption in other array elements.",
        "description": "Multiple elements of an array of values that are shorter than 17 bytes are packed into the same storage slot. Writing to a single element of such an array did not properly clean the higher order bytes and thus could lead to data corruption.",
        "severity": "medium/high",
        "fixed": "0.3.1"
    },
    {
        "name": "AncientCompiler",
        "summary": "This compiler version is ancient and might contain several undocumented or undiscovered bugs.",
        "description": "The list of bugs is only kept for compiler versions starting from 0.3.0, so older versions might contain undocumented bugs.",
        "severity": "high",
        "fixed": "0.3.0"
    }
]