I'm not professionally involved in security, so hopefully you can pardon me if I misuse any terminology or demonstrate my naivete in some other way. This question came to me as I was reading this paper on the role of language in cyber-crime. Here are some relevant excerpts from the paper:
Figure 2 reflects the fact that, although English is the most used language, Arabic, Russian, [and] Chinese users have increased over 1000% in just over ten years. These three language groups are significant in that the vast majority of cyber-crime incidents have originated in Russia and China, whereas Arabic has been more in use for other purposes.
Well-known cyber-crime groups have established mini-communities and societies centered around language...All trusted groups use language cues to establish credibility; this is a well-established socio-linguistic principle which has been documented since the 1950's.
As a disclaimer, I'm a little skeptical of the paper. For instance, when it says that "the vast majority of cyber-crime incidents have originated in Russia and China", it seems that there are a number of factors at play here that constitute "cyber-crime incidents", e.g. rate of local infections, proportion of infected web pages, and distribution of malware, and each of these categories seems to produce different statistics. I'd also assume (without evidence, so please correct me if I'm wrong) that most of what a security practitioner would deal with is domestic rather than international, and even then, I'd assume that much of what someone does online to 'attack' others (e.g. designing malware) is somewhat independent of the 'natural' languages that they speak.
Then again, when it comes to something like cryptography and decryption, perhaps language might come into play? One example that comes to mind is how British and American cryptographers intercepted and decoded Japanese ciphers at Bletchley Park during WWII. It seems this was very high-priority work back then -- enough to incite the Inter-Services Special Intelligence School to start a 6-month crash course in Japanese that lasted until the war ended (where those who completed the course would then work on decoding Japanese naval messages) -- but I'm not sure if automatic translation capabilities and such would have rendered all of this obsolete in the modern age.
I suppose that I'm ultimately interested in whether or not it is ever worthwhile to learn other languages for the purposes of tackling problems that concern information or network security. Or is language learning generally a non-useful way for a practitioner to spend their time?