# What is CVE-2023-38831?

> CVE-2023-38831 is a high-severity flaw (CVSS 7.8) in Winrar from Rarlab, published on 23 August 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 over 99%. If you run an affected version, patch it first.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2023-38831

## At a glance

- **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
- **Precursor Intelligence risk score:** 78 out of 100 (High); action: Emergency patch. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.8 out of 10)
- **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited
- **Chance of use in the next 30 days:** over 99% (latest exploit-likelihood forecast)
- **Published:** 23 August 2023
- **Record last updated:** 31 October 2025
- **Main product:** Winrar from Rarlab
- **Affected products:** 1

## What is CVE-2023-38831? In plain terms

An attacker has to be already on the device 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

RARLAB WinRAR before 6.23 allows attackers to execute arbitrary code when a user attempts to view a benign file within a ZIP archive. The issue occurs because a ZIP archive may include a benign file (such as an ordinary .JPG file) and also a folder that has the same name as the benign file, and the contents of the folder (which may include executable content) are processed during an attempt to access only the benign file. This was exploited in the wild in April through October 2023.

### What kind of flaw is it?

- CWE-345: Insufficient Verification of Data Authenticity
- CWE-351: Insufficient Type Distinction

### 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: No login needed
- Does someone have to click: Yes, a person has to take an action
- What an attacker gets: Can read data, change data and take it offline

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

## Is CVE-2023-38831 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 over 99%.

Exploit likelihood over the last 7 days: >99%, >99%, >99%, >99%, >99%, >99%, >99%.

### Timeline

- 23 August 2023: Published
- 31 October 2025: Record last updated

### How Precursor Intelligence ranks it

CVE-2023-38831 scores **78 out of 100 (High)**, with the action "Emergency patch".

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-2023-38831?

The published record lists 1 product. Versions are as published: "before 6.23" means every version up to, but not including, 6.23.

- [Winrar](https://www.precursorintelligence.com/product/rarlab/winrar) by [Rarlab](https://www.precursorintelligence.com/vendors/rarlab) (Application): before 6.23

## How do I fix CVE-2023-38831?

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 latest update from the vendor. The references list where the vendor has published details.
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. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

### References

- [packetstormsecurity.com](http://packetstormsecurity.com/files/174573/WinRAR-Remote-Code-Execution.html) (Exploit, Third-party advisory, Vulnerability database)
- [blog.google](https://blog.google/threat-analysis-group/government-backed-actors-exploiting-winrar-vulnerability/) (Exploit, Third-party advisory)
- [news.ycombinator.com](https://news.ycombinator.com/item?id=37236100) (Issue tracking)
- [bleepingcomputer.com](https://www.bleepingcomputer.com/news/security/winrar-zero-day-exploited-since-april-to-hack-trading-accounts/) (Exploit, Press/media coverage, Third-party advisory)
- [group-ib.com](https://www.group-ib.com/blog/cve-2023-38831-winrar-zero-day/) (Exploit, Press/media coverage, Third-party advisory)
- [cisa.gov](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-38831) (Government resource)

## Questions

### What is CVE-2023-38831?

CVE-2023-38831 is a high-severity flaw in Winrar from Rarlab, published on 23 August 2023. An attacker has to be already on the device 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.

### How serious is CVE-2023-38831?

It scores 7.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2023-38831 is 78 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.

### Is CVE-2023-38831 being exploited?

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 over 99%.

### Which versions does CVE-2023-38831 affect?

For Winrar from Rarlab: before 6.23.

### How do I fix CVE-2023-38831?

Install the update the vendor names in its advisory. 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.

## Does CVE-2023-38831 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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