# What is CVE-2021-33478?

> CVE-2021-33478 is a medium-severity flaw (CVSS 6.8) in IP Phone 8800 Firmware from Cisco, published on 22 July 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-2021-33478

## 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:** 24 out of 100 (Low); action: Monitor. Kept up to date as the evidence changes.
- **Severity:** Medium (CVSS 6.8 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:** 22 July 2021
- **Record last updated:** 2 August 2021
- **Main product:** IP Phone 8800 Firmware from Cisco
- **Affected products:** 15

## What is CVE-2021-33478? In plain terms

An attacker has to be physically at the device without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The official description

The TrustZone implementation in certain Broadcom MediaxChange firmware could allow an unauthenticated, physically proximate attacker to achieve arbitrary code execution in the TrustZone Trusted Execution Environment (TEE) of an affected device. This, for example, affects certain Cisco IP Phone and Wireless IP Phone products before 2021-07-07. Exploitation is possible only when the attacker can disassemble the device in order to control the voltage/current for chip pins.

### What kind of flaw is it?

- CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer

### How an attack on it works

- Where an attacker can be: Physically at the device
- How hard it is to pull off: Easy: no special conditions
- Login needed first: No login needed
- 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:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Is CVE-2021-33478 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

- 22 July 2021: Published
- 2 August 2021: Record last updated

### How Precursor Intelligence ranks it

CVE-2021-33478 scores **24 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-2021-33478?

The published record lists 15 products. Versions are as published: "before 14.0(1)" means every version up to, but not including, 14.0(1).

- [IP Phone 8800 Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8800_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 14.0(1)
- [IP Phone 8800 Series with Multiplatform Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8800_series_with_multiplatform_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 11.3(4)
- [IP Phone 8811 Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8811_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 14.0(1)
- [IP Phone 8811 with Multiplatform Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8811_with_multiplatform_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 11.3(4)
- [IP Phone 8841 Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8841_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 14.0(1)
- [IP Phone 8841 with Multiplatform Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8841_with_multiplatform_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 11.3(4)
- [IP Phone 8845 Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8845_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 14.0(1)
- [IP Phone 8845 with Multiplatform Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8845_with_multiplatform_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 11.3(4)
- [IP Phone 8851 Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8851_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 14.0(1)
- [IP Phone 8851 with Multiplatform Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8851_with_multiplatform_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 11.3(4)
- [IP Phone 8861 Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8861_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 14.0(1)
- [IP Phone 8861 with Multiplatform Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8861_with_multiplatform_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 11.3(4)
- [IP Phone 8865 Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8865_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 14.0(1)
- [IP Phone 8865 with Multiplatform Firmware](https://www.precursorintelligence.com/product/cisco/ip_phone_8865_with_multiplatform_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 11.3(4)
- [Wireless IP Phone 8821 Firmware](https://www.precursorintelligence.com/product/cisco/wireless_ip_phone_8821_firmware) by [Cisco](https://www.precursorintelligence.com/vendors/cisco) (Operating system): before 11.0(6)sr1

## How do I fix CVE-2021-33478?

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

- [tools.cisco.com](https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-brcm-mxc-jul2021-26LqUZUh) (Vendor advisory)

## Questions

### What is CVE-2021-33478?

CVE-2021-33478 is a medium-severity flaw in IP Phone 8800 Firmware from Cisco, published on 22 July 2021. An attacker has to be physically at the device without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2021-33478?

It scores 6.8 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2021-33478 is 24 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-2021-33478 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-2021-33478 affect?

For IP Phone 8800 Firmware from Cisco: before 14.0(1). The record lists 15 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2021-33478?

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-2021-33478 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.

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