Improper input validation in [UNKNOWN] python-cryptography
Priority LOW 39CWE-20Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Partial Red Hat: 1 fixed, 1 without a fix
Attack profile from CVSS 3.0 · CNA. Fix status from CNA, GitHub and Red Hat.
Summary
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.
Why it matters now
EPSS 0.03196 88th percentileScored 2026-11-07
Fix Partial cryptography (PyPI): 2.3Red Hat: 1 advisoryRed Hat: 1 fixed, 1 without a fix
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| [UNKNOWN] | python-cryptography | 2.3 | — | No fix listed | CNA |
| — | cryptography (PyPI) | 1.9.0 to before 2.3 | 2.3 | Patch available | GHSA-fcf9-3qw3-gxmj |
- python-cryptography Vendor[UNKNOWN] Affected 2.3 Fixed in — No fix listed CNA
- cryptography (PyPI) Vendor— Affected 1.9.0 to before 2.3 Fixed in 2.3 Patch available GHSA-fcf9-3qw3-gxmj
CPE configurations NVD · 3
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:cryptography:python-cryptography:*:*:*:*:*:*:*:* | 1.9.0 to before 2.3 | Vulnerable | Cryptography |
| cpe:2.3:a:redhat:openstack:13:*:*:*:*:*:*:* | 13 | Vulnerable | Red Hat |
| cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:* | 18.04 | Vulnerable | Canonical |
- cpe:2.3:a:cryptography:python-cryptography:*:*:*:*:*:*:*:* Versions 1.9.0 to before 2.3 Vulnerable ·Cryptography
- cpe:2.3:a:redhat:openstack:13:*:*:*:*:*:*:* Versions 13 Vulnerable ·Red Hat
- cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:* Versions 18.04 Vulnerable ·Canonical
Remediation
- Fix · GHSA-fcf9-3qw3-gxmj cryptography (PyPI) Fixed in 2.3 Advisory →
Red Hat 1 advisory
- RHSA-2018:3600 Released 2018-11-13 · Red Hat rating Moderatepython-cryptography security update
- Red Hat OpenStack Platform 13.0 python-cryptography-2.1.4-3.el7ost, python2-cryptography-2.1.4-3.el7ost
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat OpenStack Platform 14 (Rocky) | Affected | No fix yet |
| Red Hat OpenStack Platform 13.0 | Fixed | RHSA-2018:3600 |
Not affected: 6 products
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux OpenStack Platform 7 (Kilo)
- Red Hat OpenStack Platform 8 (Liberty)
- Red Hat OpenStack Platform 9 (Mitaka)
- Red Hat Virtualization 4
Timeline
- 2026-10-02 Threatist record created from CVE-2018-10903
- 2026-10-03 Alias added: GHSA-fcf9-3qw3-gxmj
References
Patch 2
Advisory 4
Sources
- CVE-2018-10903 · CVE Program
- CVE-2018-10903 · NVD
- FIRST EPSS
- GHSA-fcf9-3qw3-gxmj · GitHub Advisory Database · CC BY 4.0
- CVE-2018-10903 · Red Hat security data · CC BY 4.0
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