CVE-2018-10903

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure.

Exploit odds

3.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2018-07-30 16:29 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 01:34 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 3.2% in the next 30 days (EPSS).
• Severity: 7.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2018-07-30 16:29 UTC

Last modified

2026-06-17 01:34 UTC

Exploit probability

3.2% · EPSS, next 30 days

Weakness

CWE-20 · Improper input validation

Record status

Modified

Affected

• Cryptography python-cryptography < 2.3
• Redhat Openstack 13
• Canonical Ubuntu Linux 18.04

Attack profile CVSS 3.0 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2018-10903.md and follow it. Check whether this project is affected by CVE-2018-10903. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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