An MRI Tuesday afternoon showed the damage to his right Achilles.
Jackson was hurt while covering Jeremy Maclin during a drill at OTAs, according to the Eagletarian.
Leg injuries are nothing new for Jackson.
The 26-year-old suffered season-ending knee injuries his last two seasons with the Colts only playing 11 games total.
Eagles draft pick Nate Allen stepped in after Jackson went down, said the Eagletarian.
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