CVE-2025-27465 x86: Incorrect stubs exception handling for flags recovery

What is CVE-2025-27465?

CVE-2025-27465 is a medium-severity denial of service vulnerability in Xen Xen, published on 16 Jul 2025. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

Certain instructions need intercepting and emulating by Xen. In some cases Xen emulates the instruction by replaying it, using an executable stub. Some instructions may raise an exception, which is supposed to be handled gracefully. Certain replayed instructions have additional logic to set up and recover the changes to the arithmetic flags.

For replayed instructions where the flags recovery logic is used, the metadata for exception handling was incorrect, preventing Xen from handling the the exception gracefully, treating it as fatal instead.

Weakness: CWE-755

Which versions are affected by CVE-2025-27465?

It affects 1 product.

Products include Xen Xen.

How do I fix CVE-2025-27465?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2025-27465 being exploited?

There is no known exploitation of CVE-2025-27465 in the wild and no public exploit code.

Other vulnerabilities in Xen Xen

• CVE-2017-10912 Privilege escalation in n/a Critical 10.0
• CVE-2017-10918 Memory corruption in n/a Critical 10.0
• CVE-2017-10920 Memory corruption in n/a Critical 10.0
• CVE-2017-10921 Memory corruption in n/a Critical 10.0
• CVE-2025-27466 Mutiple vulnerabilities in the Viridian interface Critical 9.8

All Xen Xen vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2025-27465, DEBIAN-CVE-2025-27465, GHSA-2vp3-crwq-3fg5, SUSE-SU-2025:02471-1, UBUNTU-CVE-2025-27465, openSUSE-SU-2025:15342-1.