7-Zip: security bypass flaw under attack

What is affected

7-Zip is found on ordinary personal computers and phones, so this is not only a problem for companies. If you use it and have not updated since the fix was released, you are exposed.

7-Zip contains a protection mechanism failure vulnerability that allows remote attackers to bypass the Mark-of-the-Web security feature to execute arbitrary code in the context of the current user.

What an attacker can do

This is a security bypass flaw. It lets an attacker slip past a built-in protection, so warnings and checks that normally stop malicious content never appear.

How it is reached

Needs access to the device or a file opened on it

Access the attacker needs

No account needed

Does the victim have to do something?

Yes, the victim must open or click something

What to do

1. Update 7-Zip now. Open the update or "About" screen, install whatever is offered and restart the app or device, because the fix is not active until you do.
2. Turn on automatic updates so the next fix arrives without you having to look for it.
3. If your device is too old to receive this update, stop using the affected app for anything sensitive and plan a replacement.

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• 7-zip.orgwww.7-zip.org/history.txt

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on February 6, 2025, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by February 27, 2025, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 67% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 99.3% of all scored vulnerabilities.

Its CVSS severity score is 7.0 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

7-Zip Mark-of-the-Web Bypass Vulnerability. This vulnerability allows remote attackers to bypass the Mark-of-the-Web protection mechanism on affected installations of 7-Zip. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the handling of archived files. When extracting files from a crafted archive that bears the Mark-of-the-Web, 7-Zip does not propagate the Mark-of-the-Web to the extracted files. An attacker can leverage this vulnerability to execute arbitrary code in the context of the current user. Was ZDI-CAN-25456.