CVE-2020-25212

kernel: TOCTOU mismatch in the NFS client code

Severity Score

7.0

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

A TOCTOU mismatch in the NFS client code in the Linux kernel before 5.8.3 could be used by local attackers to corrupt memory or possibly have unspecified other impact because a size check is in fs/nfs/nfs4proc.c instead of fs/nfs/nfs4xdr.c, aka CID-b4487b935452.

Una discrepancia de TOCTOU en el código del cliente NFS en el kernel de Linux versiones anteriores a 5.8.3, podría ser usada por atacantes locales para dañar la memoria o posiblemente tener otro impacto no especificado porque una comprobación de tamaño se encuentra en el archivo fs/nfs/nfs4proc.c en lugar de fs/nfs/nfs4xdr.c, también se conoce como CID-b4487b935452.

A flaw was found in the NFSv4 implementation where when mounting a remote attacker controlled server it could return specially crafted response allow for local memory corruption and possibly privilege escalation.

*Credits: N/A

Attack Vector

Local

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Local

Attack Complexity

Medium

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2020-09-09 CVE Reserved
2020-09-09 CVE Published
2023-03-08 EPSS Updated
2024-08-04 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-787: Out-of-bounds Write

CAPEC

References (14)

URL	Tag	Source
https://lists.debian.org/debian-lts-announce/2020/09/msg00025.html	Mailing List
https://lists.debian.org/debian-lts-announce/2020/10/msg00032.html	Mailing List
https://lists.debian.org/debian-lts-announce/2020/10/msg00034.html	Mailing List
https://twitter.com/grsecurity/status/1303370421958578179	Third Party Advisory

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b4487b93545214a9db8cbf32e86411677b0cca21	2022-04-28

URL	Date	SRC
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00021.html	2022-04-28
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00035.html	2022-04-28
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00042.html	2022-04-28
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.8.3	2022-04-28
https://usn.ubuntu.com/4525-1	2022-04-28
https://usn.ubuntu.com/4527-1	2022-04-28
https://usn.ubuntu.com/4578-1	2022-04-28
https://access.redhat.com/security/cve/CVE-2020-25212	2021-05-18
https://bugzilla.redhat.com/show_bug.cgi?id=1877575	2021-05-18

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 5.8.3 Search vendor "Linux" for product "Linux Kernel" and version " < 5.8.3"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				9.0 Search vendor "Debian" for product "Debian Linux" and version "9.0"		-		Affected
Opensuse Search vendor "Opensuse"		Leap Search vendor "Opensuse" for product "Leap"				15.1 Search vendor "Opensuse" for product "Leap" and version "15.1"		-		Affected
Opensuse Search vendor "Opensuse"		Leap Search vendor "Opensuse" for product "Leap"				15.2 Search vendor "Opensuse" for product "Leap" and version "15.2"		-		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				14.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "14.04"		esm		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				16.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "16.04"		esm		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
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				20.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "20.04"		lts		Affected