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What is CVE-2019-11730?A medium-severity flaw in Firefox, explained.

Medium severity7 affected products
The short answer

CVE-2019-11730 is a medium-severity flaw (CVSS 6.5) in Firefox from Mozilla, published on 23 July 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 20%. If you run an affected version, plan in the vendor’s fix.

Check if it affects you →How to fix it

Published 23 July 2019. Record last updated 31 January 2023. We keep this page's data up to date.

What it does

What is CVE-2019-11730? In plain terms.

It can be attacked from anywhere on the internet without logging in, but a person has to take an action first. If it works, the attacker can read data.

The official description

A vulnerability exists where if a user opens a locally saved HTML file, this file can use file: URIs to access other files in the same directory or sub-directories if the names are known or guessed. The Fetch API can then be used to read the contents of any files stored in these directories and they may uploaded to a server. It was demonstrated that in combination with a popular Android messaging app, if a malicious HTML attachment is sent to a user and they opened that attachment in Firefox, due to that app's predictable pattern for locally-saved file names, it is possible to read attachments the victim received from other correspondents. This vulnerability affects Firefox ESR < 60.8, Firefox < 68, and Thunderbird < 60.8.

What kind of flaw is it?

  • UnknownUnknown
CVSS 3.1 scoreMedium · 6.5

How an attack on it works

Read straight from its severity rating, translated out of the shorthand.

  • Where an attacker can beAnywhere on the internet
  • How hard it is to pull offEasy: no special conditions
  • Login needed firstNo login needed
  • Does someone have to clickYes, a person has to take an action
  • What an attacker getsCan read data

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

Exploitation

Is CVE-2019-11730 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 20%. That can change at any time, which is why we keep watching.

Known to be exploitedNoNot on the list of exploited flaws today
Chance of use in the next 30 days20%Its EPSS score, from the latest forecast

Timeline

  1. Published
  2. Record last updated
  3. Exploit likelihood fell
How Precursor Intelligence ranks it
46out of 100Medium

CVE-2019-11730 scores 46. Action: Plan remediation.

We keep the score of every published flaw up to date as the evidence changes. Four things go into the score, and evidence that criminals are actually using it counts most. In order:

  • Evidence it is being exploitedBiggest factor
  • How severe it isStrong factor
  • How widely exposed it isSmaller factor
  • Threat activity around itSmaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score.

When CVE-2019-11730 matches software you track, it lands in your list with its score and the reasons behind it.

See your own ranked list →
Affected products

Who is affected by CVE-2019-11730? 7 products.

The published record lists 7 products from 4 vendors. Versions are shown as published: "before 68.0" means every version up to, but not including, 68.0. If you run one of these, check your version, then go to the fix below.

Remediation

How do I fix CVE-2019-11730? Four steps.

  1. Check whether you run itCompare 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 fixInstall the update named in the vendor’s advisory. We’ve put the advisories and patch notes first in the list.
  3. If you can’t patch todayFollow 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 itTrack 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

13 links
Precursor Intelligence

Does CVE-2019-11730 affect you? We'll keep checking.

Looking flaws up one at a time doesn't scale. Tell us what you run once, and we tell you which flaws matter to you, in what order, and keep watching for new ones.

  1. Tell us what you runPick your software from a list, or let us work it out from your website.
  2. We match it to every flawOver 400,000 published flaws, checked against your list.
  3. Ranked by real-world riskA 0 to 100 score, led by evidence criminals are using it.
  4. Told as soon as we knowAn alert by email, in the app or by webhook to your own tools.
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CVE-2019-11730 is a medium-severity flaw in Firefox from Mozilla, published on 23 July 2019. It can be attacked from anywhere on the internet without logging in, but a person has to take an action first. If it works, the attacker can read data.

It scores 6.5 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2019-11730 is 46 out of 100, which is Medium. Its action is "Plan remediation". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

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 20%. That can change at any time, which is why we keep watching.

For Firefox from Mozilla: before 68.0. The record lists 7 products in all, each with its versions, under "Who is affected" on this page.

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.

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