python-cryptography: GCM tag forgery via truncated tag in finalize_with_tag API
Published Jul 30, 2018
8.7
HIGHCVSS 4.0
EPSS 3.20%
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 products
- Vendor n/a Product Python-Cryptography Defaultn/a
- Version 2.3StatusaffectedConstraints-
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| n/a | Python-Cryptography | n/a |
|
Configuration 1
- ≥ 1.9.0 · < 2.3
Configuration 2
- 13
- 18.04
No data.
Red Hat OpenStack Platform 13.0 (Queens)
python-cryptography-0:2.1.4-3.el7ost
Fixed · RHSA-2018:3600
Red Hat Enterprise Linux 7
python-cryptography
Not affected
Red Hat Enterprise Linux 8
python-cryptography
Not affected
Red Hat Enterprise Linux OpenStack Platform 7 (Kilo)
python-cryptography
Not affected
Red Hat OpenStack Platform 14 (Rocky)
python-cryptography
Affected
Red Hat OpenStack Platform 8 (Liberty)
python-cryptography
Not affected
Red Hat OpenStack Platform 9 (Mitaka)
python-cryptography
Not affected
Red Hat Virtualization 4
python-cryptography
Not affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat OpenStack Platform 13.0 (Queens) | python-cryptography-0:2.1.4-3.el7ost | Fixed | RHSA-2018:3600 |
| Red Hat Enterprise Linux 7 | python-cryptography | Not affected | n/a |
| Red Hat Enterprise Linux 8 | python-cryptography | Not affected | n/a |
| Red Hat Enterprise Linux OpenStack Platform 7 (Kilo) | python-cryptography | Not affected | n/a |
| Red Hat OpenStack Platform 14 (Rocky) | python-cryptography | Affected | n/a |
| Red Hat OpenStack Platform 8 (Liberty) | python-cryptography | Not affected | n/a |
| Red Hat OpenStack Platform 9 (Mitaka) | python-cryptography | Not affected | n/a |
| Red Hat Virtualization 4 | python-cryptography | Not affected | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
Metrics
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
No CVSS v3.1 score for this CVE.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
AV:N/AC:L/Au:N/C:P/I:N/A:N
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2021–2026- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v1
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (15 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 3.20% (0.03196) | 87.67th | v5 (v2026.06.15) |
| Jun 15, 2026 | 2.60% (0.02605) | 83.31th | v5 (v2026.06.15) |
| Mar 30, 2025 | 0.33% (0.00333) | 53.15th | v4 (v2025.03.14) |
| Mar 29, 2025 | 2.48% (0.02476) | 75.44th | v4 (v2025.03.14) |
| Jul 20, 2024 | 0.18% (0.00178) | 55.45th | v3 (v2023.03.01) |
| Jul 24, 2023 | 0.18% (0.00178) | 54.11th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.14% (0.00143) | 48.38th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.02% (0.01018) | 40.69th | v2 (v2022.01.01) |
| Sep 10, 2022 | 1.02% (0.01018) | 38.88th | v2 (v2022.01.01) |
| Apr 1, 2022 | 1.02% (0.01018) | 36.86th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.02% (0.01018) | 19.50th | v2 (v2022.01.01) |
| Feb 3, 2022 | 1.04% (0.01040) | 28.32th | v1 |
| Jan 6, 2022 | 1.04% (0.01040) | 27.69th | v1 |
| Sep 1, 2021 | 1.04% (0.01040) | 64.49th | v1 |
| Apr 14, 2021 | 1.04% (0.01040) | 0.00th | v1 |
References (12)
- https://access.redhat.com/errata/RHSA-2018:3600 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2018-10903 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1602931 Issue Tracking
- https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903 x_refsource_CONFIRMIssue TrackingPatchThird Party Advisory
- https://github.com/advisories/GHSA-fcf9-3qw3-gxmj Advisory
- https://github.com/pyca/cryptography/commit/d4378e42937b56f473ddade2667f919ce32208cb
- https://github.com/pyca/cryptography/pull/4342
- https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19ef x_refsource_CONFIRMPatchThird Party Advisory
- https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2018-52.yaml
- https://nvd.nist.gov/vuln/detail/CVE-2018-10903
- https://usn.ubuntu.com/3720-1 vendor-advisoryx_refsource_UBUNTUThird Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2018-10903
| Link | Providers | Tags |
|---|---|---|
| https://access.redhat.com/errata/RHSA-2018:3600 | vendor-advisoryx_refsource_REDHAT | |
| https://access.redhat.com/security/cve/CVE-2018-10903 | Vendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1602931 | Issue Tracking | |
| https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903 | x_refsource_CONFIRMIssue TrackingPatchThird Party Advisory | |
| https://github.com/advisories/GHSA-fcf9-3qw3-gxmj | Advisory | |
| https://github.com/pyca/cryptography/commit/d4378e42937b56f473ddade2667f919ce32208cb | ||
| https://github.com/pyca/cryptography/pull/4342 | ||
| https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19ef | x_refsource_CONFIRMPatchThird Party Advisory | |
| https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2018-52.yaml | ||
| https://nvd.nist.gov/vuln/detail/CVE-2018-10903 | ||
| https://usn.ubuntu.com/3720-1 | vendor-advisoryx_refsource_UBUNTUThird Party Advisory | |
| https://www.cve.org/CVERecord?id=CVE-2018-10903 |
Change history (0)
No recorded changes yet.