Researchers say Pretty Good Privacy (PGP), a widely used method of encrypting emails has been found to suffer from a serious vulnerability.
PGP is a data encryption method sometimes added to programs that send and receive email.
Details about the vulnerability were released by the Suddeutsche Zeitung newspaper prior to a scheduled embargo.
Previously, the Electronic Frontier Foundation (EFF) had advised immediately disabling email tools that automatically decrypted PGP.
The problem had been investigated by Sebastian Schinzel, at Munster University of Applied Sciences.
After the embargo on releasing details about the vulnerability was lifted, Mr Schinzel and colleagues published their research revealing how the attack on PGP emails worked.
A website explaining the issue has also now been made public.
