CVE-2023-38831
CVE-2023-38831 is a security flaw in WinRAR, a program for opening compressed files. Attackers can run their own code on WinRAR. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 24 Aug 2023, and says ransomware gangs have used it.[1]
WinRAR is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Fixed in version 6.23 of winrar.
Description
CISA calls it a code execution in RARLAB WinRAR. In its words: “RARLAB WinRAR contains an unspecified vulnerability that allows an attacker to execute code when a user attempts to view a benign file within a ZIP archive.”[1]
The CVE record adds: “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.”[2]
The underlying weakness is CWE-351, in MITRE’s list of common software weaknesses.
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| winrar | 6.23 |
Every device with WinRAR needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 24 Aug 2023, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 14 Sep 2023 to fix it.[1] CISA says ransomware gangs have used it.
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at over 99%. That’s in the top 1% of the flaws it scores.[3]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
CISA’s required action: “Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]
- Update WinRAR now.Install the latest update from RARLAB on every device that has it, and restart when asked. Then turn on automatic updates, so the next fix arrives on its own.
- Check you’re on 6.23 or later.Fixed in version 6.23 of winrar. Anything older is what attackers are going after.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at over 99%.[3] |
See also
Other WinRAR flaws
- CVE-2025-6218: path traversal ·
- CVE-2025-8088: path traversal ·
- CVE-2018-20250: absolute path traversal ·
Other RARLAB flaws
- CVE-2022-30333, UnRAR: directory traversal ·
Added the same day
- CVE-2023-32315, Ignite Realtime Openfire: path traversal ·
Every RARLAB flaw on CISA’s list · Everything added in August 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “RARLAB WinRAR Code Execution Vulnerability”. Known Exploited Vulnerabilities Catalog, added 24 Aug 2023.
- ^ National Institute of Standards and Technology. “CVE-2023-38831 Detail”. National Vulnerability Database, published 23 Aug 2023.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.998, percentile 100.0, 31 Oct 2026.
- CVE Program. “CVE-2023-38831”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.