CVE-2025-9640 Samba: vfs_streams_xattr uninitialized memory write possible
An authenticated user can read residual memory content via uninitialized heap writes in Samba's vfs_streams_xattr module, leading to information disclosure.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-9640?
CVE-2025-9640 is a medium-severity vulnerability in Red Hat Enterprise Linux 10, published on 15 Oct 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
A flaw was found in Samba, in the vfs_streams_xattr module, where uninitialized heap memory could be written into alternate data streams. This allows an authenticated user to read residual memory content that may include sensitive data, resulting in an information disclosure vulnerability.
Weakness: CWE-908
Which versions are affected by CVE-2025-9640?
How do I fix CVE-2025-9640?
Apply the vendor's patch.
Is CVE-2025-9640 being exploited?
There is no known exploitation of CVE-2025-9640 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2025-9640, AZL-68817, AZL-68936, DEBIAN-CVE-2025-9640, DLA-4384-1, ECHO-bc79-1dde-0065 and 2 more.