OpenEXR is the reference implementation and specification for the EXR image format, widely used in the motion picture industry. In versions 3.4.0 through 3.4.12, a reachable assertion failure in the HTJ2K decode path allows a crafted HTJ2K-compressed EXR file to cause an unconditional process abort in any application that calls exr_start_read() on untrusted input, resulting in denial of service. The crash is triggered by a QCD marker whose lower five bits are zero, which OpenEXR passes into the vendored OpenJPH library while constructing the codestream and evaluating its quantization delta parameters. OpenJPH uses an assertion rather than a recoverable error to validate those bits, so any invalid value calls abort() directly and cannot be intercepted by surrounding error handling, a problem compounded by OpenEXR wrapping only its internal HT header parser in error handling while leaving the later codestream read and construction calls unprotected. This issue has been resolved in version 3.4.13.
Weakness
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
Potential Mitigations
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- If possible, choose a language or compiler that performs automatic bounds checking.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
- Use libraries or frameworks that make it easier to handle numbers without unexpected consequences.
- Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++). [REF-106]
- Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
- Use unsigned integers where possible. This makes it easier to perform validation for integer overflows. When signed integers are required, ensure that the range check includes minimum values as well as maximum values.
- Understand the programming language’s underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, “not-a-number” calculations, and how the language handles numbers that are too large or too small for its underlying representation. [REF-7]
- Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.