CVE-2018-10903

Name: CVE-2018-10903
Creator: NVD / NIST
Published: 2018-07-30T16:29:00.283+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 2.60%

Last modified Jun 17, 2026

CVE-2018-10903 is a vulnerability of currently unknown severity. 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. EPSS estimates a 2.60% chance of exploitation in the next 30 days.

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.

Metrics

EPSS Probability

2.60%

83.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Cryptography	Python-Cryptography	>= 1.9.0, < 2.3
Redhat	Openstack	13
Canonical	Ubuntu Linux	18.04

References

https://access.redhat.com/errata/RHSA-2018:3600
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903Issue Tracking, Patch, Third Party Advisory
https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19efPatch, Third Party Advisory
https://usn.ubuntu.com/3720-1/Third Party Advisory
https://access.redhat.com/errata/RHSA-2018:3600
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903Issue Tracking, Patch, Third Party Advisory
https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19efPatch, Third Party Advisory
https://usn.ubuntu.com/3720-1/Third Party Advisory

Timeline

Published: Jul 30, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2018-10903?

How severe is CVE-2018-10903?

Severity scoring for CVE-2018-10903 is pending analysis. The EPSS model estimates a 2.60% probability of exploitation in the next 30 days.

How do I fix CVE-2018-10903?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2018-10903?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST