gzip, the GNU zip compression utility, is a free and patent unencumbered replacement for the standard compress utility.
Tavis Ormandy of the Google Security Team has reported multiple vulnerabilities in gzip. A stack buffer modification vulnerability was discovered in the LZH decompression code, where a pathological data stream may result in the modification of stack data such as frame pointer, return address or saved registers. A static buffer underflow was discovered in the pack decompression support, allowing a specially crafted pack archive to underflow a .bss buffer. A static buffer overflow was uncovered in the LZH decompression code, allowing a data stream consisting of pathological huffman codes to overflow a .bss buffer. Multiple infinite loops were also uncovered in the LZH decompression code.
A remote attacker may create a specially crafted gzip archive, which when decompressed by a user or automated system exectues arbitrary code with the privileges of the user id invoking gzip. The infinite loops may be abused by an attacker to disrupt any automated systems invoking gzip to handle data decompression.
There is no known workaround at this time.
All gzip users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-arch/gzip-1.3.5-r9"