What is CVE-2021-47540?

CVE-2021-47540 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10, classified as a NULL Pointer Dereference flaw (CWE-476), affecting Linux kernel versions from 5.8 onward and patched in 5.10.84, 5.15.7 and 5.16. CVE-2021-47540 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2021-47540?

CVE-2021-47540 has a CVSS score of 5.5 out of 10, rated Medium severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Is there a patch available for CVE-2021-47540?

Yes, CVE-2021-47540 has been patched. Fixed versions include 5.10.84, 5.15.7 and 5.16. If you are running Linux kernel 5.8 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2021-47540 actively exploited?

CVE-2021-47540 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is NULL Pointer Dereference (CWE-476)?

The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/476.html

CVE-2021-47540

Medium

In the Linux kernel, the following vulnerability has been resolved: mt76: mt7915: fix NULL pointer dereference in mt7915_get_phy_mode Fix the following NULL pointer dereference in mt7915_get_phy_mode routine adding an ibss interface to the mt7915 driver. [ 101.137097] wlan0: Trigger new scan to find an IBSS to join [ 102.827039] wlan0: Creating new IBSS network, BSSID 26:a4:50:1a:6e:69 [ 103.064756] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 [ 103.073670] Mem abort info: [ 103.076520] ESR = 0x96000005 [ 103.079614] EC = 0x25: DABT (current EL), IL = 32 bits [ 103.084934] SET = 0, FnV = 0 [ 103.088042] EA = 0, S1PTW = 0 [ 103.091215] Data abort info: [ 103.094104] ISV = 0, ISS = 0x00000005 [ 103.098041] CM = 0, WnR = 0 [ 103.101044] user pgtable: 4k pages, 39-bit VAs, pgdp=00000000460b1000 [ 103.107565] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000 [ 103.116590] Internal error: Oops: 96000005 [#1] SMP [ 103.189066] CPU: 1 PID: 333 Comm: kworker/u4:3 Not tainted 5.10.75 #0 [ 103.195498] Hardware name: MediaTek MT7622 RFB1 board (DT) [ 103.201124] Workqueue: phy0 ieee80211_iface_work [mac80211] [ 103.206695] pstate: 20000005 (nzCv daif -PAN -UAO -TCO BTYPE=--) [ 103.212705] pc : mt7915_get_phy_mode+0x68/0x120 [mt7915e] [ 103.218103] lr : mt7915_mcu_add_bss_info+0x11c/0x760 [mt7915e] [ 103.223927] sp : ffffffc011cdb9e0 [ 103.227235] x29: ffffffc011cdb9e0 x28: ffffff8006563098 [ 103.232545] x27: ffffff8005f4da22 x26: ffffff800685ac40 [ 103.237855] x25: 0000000000000001 x24: 000000000000011f [ 103.243165] x23: ffffff8005f4e260 x22: ffffff8006567918 [ 103.248475] x21: ffffff8005f4df80 x20: ffffff800685ac58 [ 103.253785] x19: ffffff8006744400 x18: 0000000000000000 [ 103.259094] x17: 0000000000000000 x16: 0000000000000001 [ 103.264403] x15: 000899c3a2d9d2e4 x14: 000899bdc3c3a1c8 [ 103.269713] x13: 0000000000000000 x12: 0000000000000000 [ 103.275024] x11: ffffffc010e30c20 x10: 0000000000000000 [ 103.280333] x9 : 0000000000000050 x8 : ffffff8006567d88 [ 103.285642] x7 : ffffff8006563b5c x6 : ffffff8006563b44 [ 103.290952] x5 : 0000000000000002 x4 : 0000000000000001 [ 103.296262] x3 : 0000000000000001 x2 : 0000000000000001 [ 103.301572] x1 : 0000000000000000 x0 : 0000000000000011 [ 103.306882] Call trace: [ 103.309328] mt7915_get_phy_mode+0x68/0x120 [mt7915e] [ 103.314378] mt7915_bss_info_changed+0x198/0x200 [mt7915e] [ 103.319941] ieee80211_bss_info_change_notify+0x128/0x290 [mac80211] [ 103.326360] __ieee80211_sta_join_ibss+0x308/0x6c4 [mac80211] [ 103.332171] ieee80211_sta_create_ibss+0x8c/0x10c [mac80211] [ 103.337895] ieee80211_ibss_work+0x3dc/0x614 [mac80211] [ 103.343185] ieee80211_iface_work+0x388/0x3f0 [mac80211] [ 103.348495] process_one_work+0x288/0x690 [ 103.352499] worker_thread+0x70/0x464 [ 103.356157] kthread+0x144/0x150 [ 103.359380] ret_from_fork+0x10/0x18 [ 103.362952] Code: 394008c3 52800220 394000e4 7100007f (39400023)

Package Linux Kernel

Published 2024-05-24

Last modified 2024-11-21

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

5.5

out of 10

Medium

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

High

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness type

CWE-476

CVE-2021-47540 is a NULL Pointer Dereference vulnerability

What is NULL Pointer Dereference?

The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. Learn more on MITRE CWE

Affected versions

Linux kernel versions 5.8 and later are affected. Fixed in 5.10.84, 5.15.7, 5.16 and their respective stable series.

Affected from

≥ 5.8

Fixed in

✓ 5.10.84 5.10.x ✓ 5.15.7 5.15.x ✓ 5.16

References

3 total

Kernel Git
https://git.kernel.org/stable/c/14b03b8cebdf18ff13c39d58501b625411314de2

Patch
Kernel Git
https://git.kernel.org/stable/c/6e53d6d26920d5221d3f4d4f5ffdd629ea69aa5c

Patch
Kernel Git
https://git.kernel.org/stable/c/932b338f4e5c4cb0c2ed640da3bced1e63620198

Patch

Details

CVE ID CVE-2021-47540

Severity Medium

CVSS score 5.5 / 10

CVSS version 3.1

Published 2024-05-24

Modified 2024-11-21

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2021-47540?

CVE-2021-47540 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as a NULL Pointer Dereference flaw (CWE-476) . It affects Linux kernel versions from 5.8 onward and has been patched in 5.10.84, 5.15.7 and 5.16. CVE-2021-47540 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2021-47540?

CVE-2021-47540 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
Is there a patch available for CVE-2021-47540?

Yes. CVE-2021-47540 has been patched. Fixed versions include 5.10.84, 5.15.7 and 5.16. If you are running Linux kernel 5.8 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2021-47540 actively exploited?

No. CVE-2021-47540 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.