The decompression algorithm in zlib 1.1.3 and earlier, as used in many different utilities and packages, causes inflateEnd to release certain memory more than once (a "double free"), which may allow local and remote attackers to execute arbitrary code via a block of malformed compression data.

Buffer overflow in the gzprintf function in zlib 1.1.4, when zlib is compiled without vsnprintf or when long inputs are truncated using vsnprintf, allows attackers to cause a denial of service or possibly execute arbitrary code.

The error handling in the (1) inflate and (2) inflateBack functions in ZLib compression library 1.2.x allows local users to cause a denial of service (application crash).

inftrees.h in zlib 1.2.2 allows remote attackers to cause a denial of service (application crash) via an invalid file that causes a large dynamic tree to be produced.

zlib 1.2 and later versions allows remote attackers to cause a denial of service (crash) via a crafted compressed stream with an incomplete code description of a length greater than 1, which leads to a buffer overflow, as demonstrated using a crafted PNG file.

Race condition in pigz before 2.2.5 uses permissions derived from the umask when compressing a file before setting that file's permissions to match those of the original file, which might allow local users to bypass intended access permissions while compression is occurring.

Multiple directory traversal vulnerabilities in pigz 2.3.1 allow remote attackers to write to arbitrary files via a (1) full pathname or (2) .. (dot dot) in an archive.

inftrees.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact by leveraging improper pointer arithmetic.

inffast.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact by leveraging improper pointer arithmetic.

The crc32_big function in crc32.c in zlib 1.2.8 might allow context-dependent attackers to have unspecified impact via vectors involving big-endian CRC calculation.

zlib before 1.2.12 allows memory corruption when deflating (i.e., when compressing) if the input has many distant matches.

zlib through 1.2.12 has a heap-based buffer over-read or buffer overflow in inflate in inflate.c via a large gzip header extra field. NOTE: only applications that call inflateGetHeader are affected. Some common applications bundle the affected zlib source code but may be unable to call inflateGetHeader (e.g., see the nodejs/node reference).

MiniZip in zlib through 1.3 has an integer overflow and resultant heap-based buffer overflow in zipOpenNewFileInZip4_64 via a long filename, comment, or extra field. NOTE: MiniZip is not a supported part of the zlib product. NOTE: pyminizip through 0.2.6 is also vulnerable because it bundles an affected zlib version, and exposes the applicable MiniZip code through its compress API.

zlib versions up to and including 1.3.1.2 include a global buffer overflow in the untgz utility located under contrib/untgz. The vulnerability is limited to the standalone demonstration utility and does not affect the core zlib compression library. The flaw occurs when a user executes the untgz command with an excessively long archive name supplied via the command line, leading to an out-of-bounds write in a fixed-size global buffer.

zlib before 1.3.2 allows CPU consumption via crc32_combine64 and crc32_combine_gen64 because x2nmodp can do right shifts within a loop that has no termination condition.