NASA is reviewing Boeing's software engineering, and it doesn't like what it sees.

Lurking behind 1 million lines of code for Boeing's CST-100 Starliner spacecraft lies a deficient development process that led to two software flaws during a failed test flight, the U.S. space agency said Friday. The "critical software defects" — either of which could have caused the uncrewed Starliner's destruction — prompted NASA to open a broad review of Boeing's quality control.

"The two software issues you all know about are indicators of the software problems, but they are likely only symptoms, they are not the real problem," said Doug Loverro, the National Aeronautics and Space Administration's associate administrator overseeing human spaceflight.