Language: Go
Label: vulnerable
CWE: CWE-78 \u2014 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Code:
func (c *StreamClient) WriteL(l int) error {
	binary.BigEndian.PutUint16(c.WB[:2], uint16(l))
	c.ca.Seal(c.WB[:0], c.cn, c.WB[:2], nil)
	NextNonce(c.cn)
	c.ca.Seal(c.WB[:2+16], c.cn, c.WB[2+16:2+16+l], nil)
	if _, err := c.Server.Write(c.WB[:2+16+l+16]); err != nil {
		return err
	}
	NextNonce(c.cn)
	return nil
}