The Jargon File (version 4.4.7, 29 Dec 2003):

CLM
 /C?L?M/

    [Sun: ?Career Limiting Move?]

    1. n. An action endangering one's future prospects of getting plum projects
    and raises, and possibly one's job: ?His Halloween costume was a parody of
    his manager. He won the prize for ?best CLM?.?

    2. adj. Denotes extreme severity of a bug, discovered by a customer and
    obviously missed earlier because of poor testing: ?That's a CLM bug!?


The Free On-line Dictionary of Computing (30 December 2018):

Career Limiting Move
CLM

    (CLM, Sun) Any action endangering one's future
   prospects of getting plum projects and raises, and possibly
   one's job.  E.g. "His Halloween costume was a parody of his
   manager.  He won the prize for "best CLM"."  A severe bug
   discovered by a customer might be a "CLM bug".

   (2000-08-09)