{"cve":"CVE-2018-10903","nvd":{"published":"2018-07-30T16:29:00.283","modified":"2026-06-17T01:34:53.027","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.0","vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","score":7.5},"cwes":["CWE-20"],"references":["https://access.redhat.com/errata/RHSA-2018:3600","https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903","https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19ef","https://usn.ubuntu.com/3720-1/","https://access.redhat.com/errata/RHSA-2018:3600"],"products":["canonical:ubuntu_linux","cryptography:python-cryptography","redhat:openstack"],"source":"nvd","synced_at":"2026-10-19T20:52:03.425131697+00:00"},"epss":{"cve":"CVE-2018-10903","score":0.03196,"percentile":0.88117,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-fcf9-3qw3-gxmj","url":"https://osv.dev/vulnerability/GHSA-fcf9-3qw3-gxmj","summary":"PyCA Cryptography vulnerable to GCM tag forgery","modified":"2024-09-13T18:23:23.420507Z","packages":[{"ecosystem":"PyPI","name":"cryptography","purl":"pkg:pypi/cryptography","ranges":[">=1.9.0 <2.3"],"fixed":["2.3"]}]},{"id":"PYSEC-2018-52","url":"https://osv.dev/vulnerability/PYSEC-2018-52","summary":"","modified":"2023-11-08T03:59:44.669160Z","packages":[{"ecosystem":"PyPI","name":"cryptography","purl":"pkg:pypi/cryptography","ranges":[">=1.9 <2.3"],"fixed":["2.3"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}