CVE-2019-11841

A message-forgery issue was discovered in
crypto/openpgp/clearsign/clearsign.go in supplementary Go cryptography
libraries 2019-03-25. According to the OpenPGP Message Format specification
in RFC 4880 chapter 7, a cleartext signed message can contain one or more
optional “Hash” Armor Headers. The “Hash” Armor Header specifies the
message digest algorithm(s) used for the signature. However, the Go
clearsign package ignores the value of this header, which allows an
attacker to spoof it. Consequently, an attacker can lead a victim to
believe the signature was generated using a different message digest
algorithm than what was actually used. Moreover, since the library skips
Armor Header parsing in general, an attacker can not only embed arbitrary
Armor Headers, but also prepend arbitrary text to cleartext messages
without invalidating the signatures.

Bugs

• <https://bugs.launchpad.net/ubuntu/+source/golang-pault-go-archive/+bug/1828905&gt;

Notes