Aircompressor is a library with ports of the Snappy, LZO, LZ4, and Zstandard compression algorithms to Java. In versions 3.3 and below, incorrect handling of malformed data in Java-based decompressor implementations for Snappy and LZ4 allow remote attackers to read previous buffer contents via crafted compressed input. With certain crafted compressed inputs, elements from the output buffer can end up in the uncompressed output, potentially leaking sensitive data. This is relevant for applications that reuse the same output buffer to uncompress multiple inputs. This can be the case of a web server that allocates a fix-sized buffer for performance purposes. There is similar vulnerability in GHSA-cmp6-m4wj-q63q. This issue is fixed in version 3.4.
Weakness
The product reads data past the end, or before the beginning, of the intended buffer.
Potential Mitigations
- 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.
- To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.
References