CS-DOS, along with an assortment of other named exploits such as hlfreeze and headnut, consist of malformed packets designed to get Half-Life servers stuck in an infinite loop
CS DOS Fix not enjoyed as much success as hlboom. It is less likely to succeed and script kiddies can often be thwarted without fixing the problem. Unfortunately patches for CS-DOS have not been as thoroughly tested for all versions.
Aluigi provides a file for his Lame Patcher Program which will patch the bug in memory. His patch is available here and fixes Windows and Linux servers of version x.1.1.1e. The Half-Life Winsock dll and C files mentioned on the HL_Boom page " V5.steamlessproject.nl " should also protect against CS-DOS. This has not been sufficiently tested. If you are suffering from CS-DOS attacks and use these patches please report your findings.
If you encounter problems please report them in the Support forums.
V5.steamlessproject.nl
