Which ISO/IEC committee is responsible for the 27000-series information security standards?

ISO/IEC JTC 1/SC 27 — Information security, cybersecurity and privacy protection — a sub-committee of the Joint Technical Committee on Information Technology.

* The SC 27 reporting tree: ISO and IEC jointly own JTC 1, whose SC 27 subcommittee and its working groups author the entire 27000 series. *

The reporting chain:

ISO + IEC
   │
JTC 1   (Information Technology)
   │
SC 27  (Information security, cybersecurity and privacy protection)
   │
WGs    (Working Groups for specific topics)

SC 27 was created in 1989, secretariat is DIN (Germany). It owns the entire ISO/IEC 27000-series, but its scope is broader:

• Security requirements capture
• Management of information / ICT security (ISMS standards)
• Cryptographic mechanisms (key management, digital signatures)
• Security support documentation
• Identity management, biometrics, privacy
• Conformance assessment
• Security evaluation criteria

Tip: The German secretariat is the reason BSI engineers have outsized influence on the ISO 27k series — many ISO 27k authors are also BSI Grundschutz authors. This explains why the ISO 27k and BSI worlds are conceptually so close.

Go deeper:

• ISO/IEC JTC 1/SC 27 (Wikipedia) — the subcommittee's working groups (WG1-WG5), DIN secretariat and the 27k series it owns.