# What is CVE-2021-3843?

> CVE-2021-3843 is a medium-severity flaw (CVSS 6.7) in Thinkpad 11e 3rd Gen Firmware from Lenovo, published on 12 November 2021. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 0.3%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2021-3843

## At a glance

- **Verdict:** Plan it in. No sign of exploitation and a low forecast. Patch it in your normal update cycle.
- **Precursor Intelligence risk score:** 23 out of 100 (Low); action: Monitor. Kept up to date as the evidence changes.
- **Severity:** Medium (CVSS 6.7 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 0.3% (latest exploit-likelihood forecast)
- **Published:** 12 November 2021
- **Record last updated:** 23 November 2021
- **Main product:** Thinkpad 11e 3rd Gen Firmware from Lenovo
- **Affected products:** 59

## What is CVE-2021-3843? In plain terms

An attacker has to be already on the device with an administrator account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The official description

A potential vulnerability in the SMI function to access EEPROM in some ThinkPad models may allow an attacker with local access and elevated privileges to execute arbitrary code.

### What kind of flaw is it?

- CWE-20: Improper Input Validation

### How an attack on it works

- Where an attacker can be: Already on the device
- How hard it is to pull off: Easy: no special conditions
- Login needed first: An administrator account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

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

## Is CVE-2021-3843 being exploited? Not that we know of

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.3%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 0.3%, 0.3%, 0.3%, 0.3%, 0.3%, 0.3%, 0.3%.

### Timeline

- 12 November 2021: Published
- 23 November 2021: Record last updated

### How Precursor Intelligence ranks it

CVE-2021-3843 scores **23 out of 100 (Low)**, with the action "Monitor".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2021-3843?

The published record lists 59 products. Versions are as published: "before 1.20.1.17" means every version up to, but not including, 1.20.1.17.

- [Thinkpad 11e 3rd Gen Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_3rd_gen_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.22, up to 1.29
- [Thinkpad L13 Gen 2 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l13_gen_2_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.11, up to 1.08
- [Thinkpad L13 Yoga Gen 2 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l13_yoga_gen_2_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.11, up to 1.08
- [Thinkpad 11e 3rd Gen](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_3rd_gen) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad 11e 4th Gen Celeron](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_4th_gen_celeron) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad 11e 4th Gen Celeron Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_4th_gen_celeron_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.27
- [Thinkpad 11e 4th Gen I3](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_4th_gen_i3) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad 11e 4th Gen I3 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_4th_gen_i3_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.22
- [Thinkpad 11e 4th Gen I5](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_4th_gen_i5) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad 11e 4th Gen I5 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_4th_gen_i5_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.22
- [Thinkpad 11e 4th Gen I7](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_4th_gen_i7) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad 11e 4th Gen I7 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_4th_gen_i7_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.22
- [Thinkpad 11e 5th Gen](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_5th_gen) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad 11e 5th Gen Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_5th_gen_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.13
- [Thinkpad 11e Yoga Gen 6](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_yoga_gen_6) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad 11e Yoga Gen 6 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_11e_yoga_gen_6_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.12
- [Thinkpad 13 Gen 2](https://www.precursorintelligence.com/product/lenovo/thinkpad_13_gen_2) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad 13 Gen 2 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_13_gen_2_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.29
- [Thinkpad L13](https://www.precursorintelligence.com/product/lenovo/thinkpad_l13) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L13 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l13_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.31
- [Thinkpad L13 Gen 2](https://www.precursorintelligence.com/product/lenovo/thinkpad_l13_gen_2) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L13 Yoga](https://www.precursorintelligence.com/product/lenovo/thinkpad_l13_yoga) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L13 Yoga Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l13_yoga_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.31
- [Thinkpad L13 Yoga Gen 2](https://www.precursorintelligence.com/product/lenovo/thinkpad_l13_yoga_gen_2) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L14](https://www.precursorintelligence.com/product/lenovo/thinkpad_l14) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L14 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l14_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): before 1.20.1.17
- [Thinkpad L14 Gen 1](https://www.precursorintelligence.com/product/lenovo/thinkpad_l14_gen_1) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L14 Gen 1 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l14_gen_1_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): before 1.15
- [Thinkpad L15](https://www.precursorintelligence.com/product/lenovo/thinkpad_l15) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L15 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l15_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): before 1.20.1.17
- [Thinkpad L15 Gen 1](https://www.precursorintelligence.com/product/lenovo/thinkpad_l15_gen_1) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L15 Gen 1 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l15_gen_1_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): before 1.15
- [Thinkpad L380](https://www.precursorintelligence.com/product/lenovo/thinkpad_l380) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L380 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l380_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.26
- [Thinkpad L380 Yoga](https://www.precursorintelligence.com/product/lenovo/thinkpad_l380_yoga) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L380 Yoga Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l380_yoga_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.26
- [Thinkpad L390](https://www.precursorintelligence.com/product/lenovo/thinkpad_l390) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L390 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l390_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.35
- [Thinkpad L390 Yoga](https://www.precursorintelligence.com/product/lenovo/thinkpad_l390_yoga) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad L390 Yoga Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_l390_yoga_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.35
- [Thinkpad S2 Gen 6](https://www.precursorintelligence.com/product/lenovo/thinkpad_s2_gen_6) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad S2 Gen 6 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_s2_gen_6_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 2021-09-30
- [Thinkpad S2 Yoga Gen 6](https://www.precursorintelligence.com/product/lenovo/thinkpad_s2_yoga_gen_6) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad S2 Yoga Gen 6 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_s2_yoga_gen_6_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 2021-09-30
- [Thinkpad S5 2nd Gen](https://www.precursorintelligence.com/product/lenovo/thinkpad_s5_2nd_gen) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad S5 2nd Gen Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_s5_2nd_gen_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.28
- [Thinkpad T460](https://www.precursorintelligence.com/product/lenovo/thinkpad_t460) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad T460 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_t460_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.43.1.11
- [Thinkpad X1 Fold Gen 1](https://www.precursorintelligence.com/product/lenovo/thinkpad_x1_fold_gen_1) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad X1 Fold Gen 1 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_x1_fold_gen_1_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): before n2pet50w
- [Thinkpad X12 Detachable Gen 1](https://www.precursorintelligence.com/product/lenovo/thinkpad_x12_detachable_gen_1) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad X12 Detachable Gen 1 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_x12_detachable_gen_1_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): before 1.16
- [Thinkpad X260](https://www.precursorintelligence.com/product/lenovo/thinkpad_x260) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad X260 Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_x260_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.47/1.15
- [Thinkpad X380 Yoga](https://www.precursorintelligence.com/product/lenovo/thinkpad_x380_yoga) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad X380 Yoga Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_x380_yoga_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): up to 1.34
- [Thinkpad X390 Yoga](https://www.precursorintelligence.com/product/lenovo/thinkpad_x390_yoga) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified
- [Thinkpad X390 Yoga Firmware](https://www.precursorintelligence.com/product/lenovo/thinkpad_x390_yoga_firmware) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Operating system): before n2let87w
- [Thinkpad Yoga 370](https://www.precursorintelligence.com/product/lenovo/thinkpad_yoga_370) by [Lenovo](https://www.precursorintelligence.com/vendors/lenovo) (Hardware): version not specified

## How do I fix CVE-2021-3843?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

### References

- [support.lenovo.com](https://support.lenovo.com/us/en/product_security/LEN-72619) (Vendor advisory)

## Questions

### What is CVE-2021-3843?

CVE-2021-3843 is a medium-severity flaw in Thinkpad 11e 3rd Gen Firmware from Lenovo, published on 12 November 2021. An attacker has to be already on the device with an administrator account, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2021-3843?

It scores 6.7 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2021-3843 is 23 out of 100, which is Low. Its action is "Monitor". No sign of exploitation and a low forecast. Patch it in your normal update cycle.

### Is CVE-2021-3843 being exploited?

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 0.3%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2021-3843 affect?

For Thinkpad 11e 3rd Gen Firmware from Lenovo: up to 1.22, up to 1.29. The record lists 59 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2021-3843?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

## Does CVE-2021-3843 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

Start free (no card, nothing to install): https://www.precursorintelligence.com/register
Book a demo: https://www.precursorintelligence.com/contact