# What is CVE-2018-7851?

> CVE-2018-7851 is a medium-severity flaw (CVSS 6.5) in 140cra312xxx from Schneider-Electric, published on 22 May 2019. 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 1.2%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2018-7851

## 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:** 30 out of 100 (Low); action: Monitor. Kept up to date as the evidence changes.
- **Severity:** Medium (CVSS 6.5 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:** 1.2% (latest exploit-likelihood forecast)
- **Published:** 22 May 2019
- **Record last updated:** 10 April 2024
- **Main product:** 140cra312xxx from Schneider-Electric
- **Affected products:** 41

## What is CVE-2018-7851? In plain terms

It can be attacked from anywhere on the internet with an ordinary user account, and nobody has to click anything. If it works, the attacker can take it offline.

### The official description

CWE-119: Buffer errors vulnerability exists in Modicon M580 with firmware prior to V2.50, Modicon M340 with firmware prior to V3.01, BMxCRA312xx with firmware prior to V2.40, All firmware versions of Modicon Premium and 140CRA312xxx when sending a specially crafted Modbus packet, which could cause a denial of service to the device that would force a restart to restore availability.

### 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: Anywhere on the internet
- How hard it is to pull off: Easy: no special conditions
- Login needed first: An ordinary user account
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can take it offline

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

## Is CVE-2018-7851 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 1.2%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 1.2%, 1.2%, 1.2%, 1.2%, 1.2%, 1.2%, 1.2%.

### Timeline

- 22 May 2019: Published
- 10 April 2024: Record last updated

### How Precursor Intelligence ranks it

CVE-2018-7851 scores **30 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-2018-7851?

The published record lists 41 products. Versions are as published: "before 2.40" means every version up to, but not including, 2.40.

- [140cra312xxx](https://www.precursorintelligence.com/product/schneider-electric/140cra312xxx) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [140cra312xxx Firmware](https://www.precursorintelligence.com/product/schneider-electric/140cra312xxx_firmware) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Operating system): all versions
- [Bmeh582040](https://www.precursorintelligence.com/product/schneider-electric/bmeh582040) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Bmeh582040c](https://www.precursorintelligence.com/product/schneider-electric/bmeh582040c) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Bmeh584040](https://www.precursorintelligence.com/product/schneider-electric/bmeh584040) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Bmeh584040c](https://www.precursorintelligence.com/product/schneider-electric/bmeh584040c) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Bmeh586040](https://www.precursorintelligence.com/product/schneider-electric/bmeh586040) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Bmeh586040c](https://www.precursorintelligence.com/product/schneider-electric/bmeh586040c) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- Bmx/e Cra Firmware by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Operating system): before 2.40
- [Bmxcra31200](https://www.precursorintelligence.com/product/schneider-electric/bmxcra31200) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Bmxcra31210c](https://www.precursorintelligence.com/product/schneider-electric/bmxcra31210c) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [M340 Firmware](https://www.precursorintelligence.com/product/schneider-electric/m340_firmware) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Operating system): before 3.01
- [M580 Firmware](https://www.precursorintelligence.com/product/schneider-electric/m580_firmware) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Operating system): before 2.50
- [Modicon M340 Bmxp341000](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp341000) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M340 Bmxp341000h](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp341000h) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M340 Bmxp342000](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp342000) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M340 Bmxp3420102](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp3420102) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M340 Bmxp3420102cl](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp3420102cl) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M340 Bmxp342020](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp342020) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M340 Bmxp342020h](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp342020h) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M340 Bmxp3420302](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp3420302) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M340 Bmxp3420302cl](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp3420302cl) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M340 Bmxp3420302h](https://www.precursorintelligence.com/product/schneider-electric/modicon_m340_bmxp3420302h) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep581020](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep581020) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep581020h](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep581020h) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep582020](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep582020) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep582020h](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep582020h) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep582040](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep582040) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep582040h](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep582040h) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep582040s](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep582040s) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep583020](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep583020) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep583040](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep583040) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep584020](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep584020) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep584040](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep584040) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep584040s](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep584040s) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep585040](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep585040) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep585040c](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep585040c) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep586040](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep586040) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon M580 Bmep586040c](https://www.precursorintelligence.com/product/schneider-electric/modicon_m580_bmep586040c) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon Premium](https://www.precursorintelligence.com/product/schneider-electric/modicon_premium) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Hardware): version not specified
- [Modicon Premium Firmware](https://www.precursorintelligence.com/product/schneider-electric/modicon_premium_firmware) by [Schneider-Electric](https://www.precursorintelligence.com/vendors/schneider-electric) (Operating system): all versions

## How do I fix CVE-2018-7851?

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

- [schneider-electric.com](https://www.schneider-electric.com/en/download/document/SEVD-2019-134-10/) (Vendor advisory)

## Questions

### What is CVE-2018-7851?

CVE-2018-7851 is a medium-severity flaw in 140cra312xxx from Schneider-Electric, published on 22 May 2019. It can be attacked from anywhere on the internet with an ordinary user account, and nobody has to click anything. If it works, the attacker can take it offline.

### How serious is CVE-2018-7851?

It scores 6.5 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2018-7851 is 30 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-2018-7851 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 1.2%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2018-7851 affect?

For 140cra312xxx from Schneider-Electric: version not specified. The record lists 41 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2018-7851?

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-2018-7851 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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