CVE-2018-10903

python-cryptography: GCM tag forgery via truncated tag in finalize_with_tag API

Severity Score

7.5

*CVSS v3

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

Se ha encontrado un error en python-cryptography, desde la versión 1.9.0 hasta la 2.3. La API finalize_with_tag no forzaba una longitud de etiqueta mínima. Si un usuario no validaba la longitud de la entrada antes de pasarla a finalize_with_tag, un atacante podría manipular una carga útil no válida con una etiqueta acortada (p.ej., 1 byte) para así tener 1 posibilidad entre 256 de pasar la comprobación MAC. Las falsificaciones de etiquetas GCM pueden provocar un filtrado de claves.

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

None

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2018-05-09 CVE Reserved
2018-07-23 CVE Published
2023-07-24 EPSS Updated
2024-08-05 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-20: Improper Input Validation

CAPEC

References (6)

URL	Tag	Source

URL	Date	SRC

URL	Date	SRC
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-10903	2021-08-04
https://github.com/pyca/cryptography/pull/4342/commits/688e0f673bfbf43fa898994326c6877f00ab19ef	2021-08-04

URL	Date	SRC
https://access.redhat.com/errata/RHSA-2018:3600	2021-08-04
https://usn.ubuntu.com/3720-1	2021-08-04
https://access.redhat.com/security/cve/CVE-2018-10903	2018-11-13
https://bugzilla.redhat.com/show_bug.cgi?id=1602931	2018-11-13

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Cryptography Search vendor "Cryptography"		Python-cryptography Search vendor "Cryptography" for product "Python-cryptography"				>= 1.9.0 < 2.3 Search vendor "Cryptography" for product "Python-cryptography" and version " >= 1.9.0 < 2.3"		-		Affected
Redhat Search vendor "Redhat"		Openstack Search vendor "Redhat" for product "Openstack"				13 Search vendor "Redhat" for product "Openstack" and version "13"		-		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				18.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "18.04"		lts		Affected