Double free in Linux kernel Xen privcmd via VMA splitting
CVE-2026-31787 is a double-free vulnerability in the Linux kernel Xen privcmd driver. The flaw arises because privcmd_vm_ops defines a .close handler (privcmd_close) but does not define .may_split or .open. When userspace performs a partial munmap() on a privcmd mapping, the kernel may split the VMA via __split_vma(). Because .may_split is absent, the split is permitted, and vm_area_dup() duplicates vm_private_data into the new VMA without reinitialization or reference management. As a result, both VMAs reference the same pages array originally allocated by alloc_empty_pages(). When one VMA is closed, privcmd_close() invokes xen_unmap_domain_gfn_range(), xen_free_unpopulated_pages(), and kvfree(pages). The remaining VMA retains a dangling pointer, and when it is later destroyed, the same cleanup path executes again, causing a double free of kernel memory. Xen tracks this as XSA-487.
Are you exposed to this one?
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Linux kernel double-free in the Xen privcmd driver; it requires root privileges and is described by the Xen Project as not security-relevant beyond crash potential.
A Linux kernel double-free in the Xen privcmd driver; although it can crash the system, it requires root privileges and is described as not security-relevant by the Xen Project.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.