CVE-2018-10903
HIGH7.5EPSS 0.24%PyCA Cryptography vulnerable to GCM tag forgery
Published: 7/31/2018Modified: 4/28/2026
Also known as:DEBIAN-CVE-2018-10903
Description
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.
Affected packages (3)
- Debian/python-cryptographyfrom 0, < 2.3-1
- PyPI/cryptography>= 1.9.0, < 2.3
- PyPI/cryptography>= 1.9, < 2.3
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N |
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N |
References (12)
- ADVISORYhttps://github.com/advisories/GHSA-fcf9-3qw3-gxmj
- ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2018-10903
- ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2018-10903
- PATCHhttps://github.com/pyca/cryptography
- WEBhttps://access.redhat.com/errata/RHSA-2018:3600
- WEBhttps://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903
- WEBhttps://github.com/pyca/cryptography/commit/d4378e42937b56f473ddade2667f919ce32208cb
- WEBhttps://github.com/pyca/cryptography/pull/4342
- WEBhttps://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19ef
- WEBhttps://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2018-52.yaml
- WEBhttps://usn.ubuntu.com/3720-1
- WEBhttps://usn.ubuntu.com/3720-1/