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CVE-2018-10903

HIGH
Published 2018-07-30T15:00:00
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CVSS Score

V3.0
7.5
/10
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Base Score Metrics
Exploitability: N/A Impact: N/A

EPSS Score

v2025.03.14
0.003
probability
of exploitation in the wild

There is a 0.3% chance that this vulnerability will be exploited in the wild within the next 30 days.

Updated: 2025-06-25
Exploit Probability
Percentile: 0.484
Higher than 48.4% of all CVEs

Attack Vector Metrics

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED

Impact Metrics

Confidentiality
HIGH
Integrity
NONE
Availability
NONE

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.

Available Exploits

No exploits available for this CVE.

Related News

No news articles found for this CVE.

Affected Products

[UNKNOWN]

python-cryptography

Affected Versions:

2.3

GitHub Security Advisories

Community-driven vulnerability intelligence from GitHub

✓ GitHub Reviewed HIGH

PyCA Cryptography vulnerable to GCM tag forgery

GHSA-fcf9-3qw3-gxmj

Advisory Details

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

PyPI cryptography
ECOSYSTEM: ≥1.9.0 <2.3

CVSS Scoring

CVSS Score

7.5

CVSS Vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References

ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2018-10903
WEB https://github.com/pyca/cryptography/pull/4342
WEB https://github.com/pyca/cryptography/commit/d4378e42937b56f473ddade2667f919ce32208cb
WEB https://access.redhat.com/errata/RHSA-2018:3600
WEB https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903
ADVISORY https://github.com/advisories/GHSA-fcf9-3qw3-gxmj
PACKAGE https://github.com/pyca/cryptography
WEB https://github.com/pypa/advisory-database/tree/main/vulns/cryptography/PYSEC-2018-52.yaml
WEB https://usn.ubuntu.com/3720-1

Advisory provided by GitHub Security Advisory Database. Published: July 31, 2018, Modified: September 13, 2024

References

https://access.redhat.com/errata/RHSA-2018:3600
https://usn.ubuntu.com/3720-1/
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903
https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19ef
Published: 2018-07-30T15:00:00
Last Modified: 2024-08-05T07:54:36.330Z
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