GHSA-fcf9-3qw3-gxmj
PyCA Cryptography vulnerable to GCM tag forgery
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| PyPI | cryptography | >= 1.9.0, < 2.3 | 2.3 |
Details
As written in the advisory (Markdown source, shown as plain text).
A flaw was found in python-cryptography versions between >=1.9.0 and <2.3. The finalize_with_tag API did not enforce a minimum tag length. If a user did not validate the input length prior to passing it to finalize_with_tag an attacker could craft an invalid payload with a shortened tag (e.g. 1 byte) such that they would have a 1 in 256 chance of passing the MAC check. GCM tag forgeries can cause key leakage.
References
External links from the advisory. They lead to third-party sites.
- https://nvd.nist.gov/vuln/detail/CVE-2018-10903
- https://github.com/pyca/cryptography/pull/4342
- https://github.com/pyca/cryptography/commit/d4378e42937b56f473ddade2667f919ce32208cb
- https://access.redhat.com/errata/RHSA-2018:3600
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903
- https://github.com/advisories/GHSA-fcf9-3qw3-gxmj
- https://github.com/pyca/cryptography
- https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2018-52.yaml
- https://usn.ubuntu.com/3720-1