Adobe Acrobat and Reader: memory corruption flaw under attack

What is affected

Adobe Acrobat and Reader 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.

Adobe Acrobat and Reader contains an out-of-bounds write vulnerability that allows for code execution.

What an attacker can do

This is a memory corruption flaw. It lets an attacker corrupt the program's memory by feeding it specially crafted content: a web page, a file or a network message. The result ranges from a crash to the attacker running their own code.

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 Adobe Acrobat and Reader 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

• helpx.adobe.comhelpx.adobe.com/security/products/acrobat/apsb23-34.html

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on September 14, 2023, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by October 5, 2023, 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 6.7% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 94% of all scored vulnerabilities.

Its CVSS severity score is 7.8 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

Acrobat Reader versions 23.003.20284 (and earlier), 20.005.30516 (and earlier) and 20.005.30514 (and earlier) are affected by an out-of-bounds write vulnerability that could result in arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.