Description
In the Bouncy Castle JCE Provider version 1.55 and earlier ECDSA does not fully validate ASN.1 encoding of signature on verification. It is possible to inject extra elements in the sequence making up the signature and still have it validate, which in some cases may allow the introduction of 'invisible' data into a signed structure.
Remediation
References
https://access.redhat.com/errata/RHSA-2018:2669
https://access.redhat.com/errata/RHSA-2018:2927
https://github.com/bcgit/bc-java/commit/843c2e60f67d71faf81d236f448ebbe56c62c647#diff-25c3c78db788365f36839b3f2d3016b9
https://lists.debian.org/debian-lts-announce/2018/07/msg00009.html
https://security.netapp.com/advisory/ntap-20181127-0004/
https://usn.ubuntu.com/3727-1/
https://www.oracle.com/security-alerts/cpuoct2020.html