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What is CVE-2023-42917?A high-severity flaw criminals are using now.

High severityKnown exploited7 affected products
The short answer

CVE-2023-42917 is a high-severity flaw (CVSS 8.8) in Safari from Apple, published on 30 November 2023. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 9.3%. If you run an affected version, patch it first.

Check if it affects you →How to fix it

Published 30 November 2023. Record last updated 23 October 2025. We keep this page's data up to date.

What it does

What is CVE-2023-42917? 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, change data and take it offline.

The official description

A memory corruption vulnerability was addressed with improved locking. This issue is fixed in iOS 17.1.2 and iPadOS 17.1.2, macOS Sonoma 14.1.2, Safari 17.1.2. Processing web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been exploited against versions of iOS before iOS 16.7.1.

What kind of flaw is it?

  • CWE-787Out-of-bounds Write
CVSS 3.1 scoreHigh · 8.8

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, change data and take it offline

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

Exploitation

Is CVE-2023-42917 being exploited? Yes.

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 9.3%.

Known to be exploitedYesOn the government list of exploited flaws
Chance of use in the next 30 days9.3%Its EPSS score, from the latest forecast

Timeline

  1. Published
  2. Record last updated
How Precursor Intelligence ranks it
76out of 100High

CVE-2023-42917 scores 76. Action: Emergency patch.

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-2023-42917 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-2023-42917? 7 products.

The published record lists 7 products from 4 vendors. Versions are shown as published: "before 17.1.2" means every version up to, but not including, 17.1.2. If you run one of these, check your version, then go to the fix below.

  • Application

    Safari

    by Apple

    Affected versions
    before 17.1.2
  • Operating system

    iPadOS

    by Apple

    Affected versions
    before 15.8.116.0 to before 16.7.317.0 to before 17.1.2
  • Operating system

    iOS

    by Apple

    Affected versions
    before 15.8.116.0 to before 16.7.317.0 to before 17.1.2
  • Operating system

    Debian Linux

    by Debian

    Affected versions
    11.012.0
  • Operating system

    Fedora

    by Fedoraproject

    Affected versions
    3839
  • Operating system

    macOS

    by Apple

    Affected versions
    14.0 to before 14.1.2
  • Application

    Webkitgtk+

    by Webkitgtk

    Affected versions
    before 2.42.3
Remediation

How do I fix CVE-2023-42917? 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. Check it wasn’t used before you patchedBecause criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

References

19 links
Precursor Intelligence

Does CVE-2023-42917 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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FAQ

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CVE-2023-42917 is a high-severity flaw in Safari from Apple, published on 30 November 2023. 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, change data and take it offline.

It scores 8.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2023-42917 is 76 out of 100, which is High. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 9.3%.

For Safari from Apple: before 17.1.2. 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. Because criminals are already using it, also check affected systems for signs of a break-in.

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